General Flashcards

Question

Carbonate Gems

Answer 1

[M⁺](CO₃)_x These are very soft and non-resilient

Answer 2

This is a penetration twin that shows 180^o rotation about the [001] axis. It is characteristic of orthoclase.

Answer 3

Cathodeluminescence is using a beam of electrons to create excitation within an atom. It is used in diamond to identify the growth patterns

Answer 4

These are reflections perpendicular to long acicular needles within stones that are oriented parallel to one another. It is only obvious when cut as a cabachon. It can only be seen when the light is perpendicular to the stone.

Answer 5

This occurs in moonstone and it looks like elongated snowflakes.

Answer 6

These are used to produce "synthetic" turquoise, lapis lazuli, and coral using a sintering process to solidify a powdered material.

Answer 7

Fundamentally [M⁺]O_x High hardness and resistance to injury/chemical attack

Answer 8

Emission lines: Ruby has a red emission line and green is missing Sharp lines: REE's Fe: cut off of red, missing yellow

Answer 9

Chrysoberyl, quartz, tourmaline, glass with optical fibers

Answer 10

Yield: maximized Transparency: Transparent stones are faceted, translucent and opaque stones are cut as cabochons, beds, carvings, or inlay Fire and Brilliance: Facets maximize the best dispersion Inclusions: Some cuts highlight inclusions other hide. Optical Effects: Usually with cabochons (chatoyancy) Color: Maximize attractiveness and utilize pleochroic properties (tourmaline) Physical constraints: Cleavage, anisotropic hardness, durability

Answer 11

Ruby: red, emerald: green, green jadeite jade: bright green, alexandrite: red/green, red spinel

Answer 12

This is defined as the plane of weakest atomic bonding. It is a sub-set of fracturing and is dependent of the crystal system and structure. It is very important for cutting and faceting gems.

Answer 13

none: obsidian, quartz (fracture) 2 directions: orthoclase, amphibole 3: galena (90^o), calcite (105, 75) 4: Fluorite

Answer 14

This is the application of a colored layer to change or improve the colour of the gem. This commonly includes quartz, topaz, cubic zirconia, and diamonds.

Answer 15

They durability of various coatings is variable and on older stones they may begin to curl or flake particularly along facet edges. Looking at the back of the stone can show the film's iridescence and the spectrum is likely influenced of the coating and not of the stone. It will be abnormal.

Answer 16

This occurs in corundum, spinel, garnet, fluorite, and zircon. Of note is alexandrite that rarely shows color change and is very desirable. Color change is the optical phenomena where stones change color based on the light source. Most commonly this is either incandescent (tungsten bulbs) and sunlight

Answer 17

The source of white light, modifications to said light, and the eye/brain's interpretation of the light.

Answer 18

This includes structural related coloration of stones due to different trace or transition elements.

Answer 19

Corundum is trigonal and will have triangles on the upper face if tabular or will be bipyramidal or barrel shaped. All forms have a tendency to have striations on the sides and hexagonal color zoning.

Answer 20

mineral = gem Spessartine = spessartite zoisite = tanzanite beryl = emerald Corundum = Sapphire/Ruby Cordierite = Iolite

Answer 21

Vesicular Textures: There are "bubble formations" due to off-gassing of relatively low-gas lava Pyroclastic: These include the explosive debris of volcanic eruptions.

Answer 22

These are materials that composed of two (doublets) or three (triplets) stones/pieces. They are generally plates of material acting as backing or on the surface providing a false front.

Answer 23

These are artificially assembled from two or more natural or artificial components meant to replicate a single gem material.

Answer 24

This is a glass ball that is used to find interference figures, which occur along the c axis of the stone, from a material in the polariscope. Used to identify if the anisotropic/doubly refractive stone is uniaxial or biaxial.

Answer 25

When rotating the stone in polarized light look for interference colors (iridescence). When noted touch the conoscope to that part of the stone and look to see if the stone is uniaxial or biaxial.

Answer 26

The total number of atoms surrounding a central cation in a molecule

Answer 27

Red Coral: Classic Mediterranean coral that is very pricey Black Coral: Hawaiian coral. It always has bumps/dots. Also pricey. Caribbean black coral is a psuedo-simulant that is worth about 100x less. Golden Corals: These are deepwater corals often dyed

Answer 28

Heating pink sapphires in the presence of beryllium shifts their color to orange. Similar processes with various other small radii elements fill vacancies and create other colors. This can leave a rind of low diffusion/high conentration.

Answer 29

Look at the symmetry, proportions, and polish

Answer 30

This is i_c and it represents when the refracted ray is at the interface of the two materials so r=90^o it occurs at sin^-1(n_r/n_i) where n is the refractive index

Answer 31

This is the angle between horizontal and the area below the girdle, it determines dispersion. If it is over 42^o then you can see straight through the diamond (lack of dispersion) and if it is less than 42^o then the girdle is refelcted to create a "fish eye"

Answer 32

Granular: Like marble or granite Lamellar/foliated/micaceous: mica colloform/stalactitic: cave deposits geode oolitic: iron ore radiating: wavellite

Answer 33

This is how minerals display crystal faces dependent upon their growth environment. It is described by the general shape of the crystal. Types: Acicular: slender needles Bipyramidal Botryoidal or globular: Hemispherical masses Columnar or Fibrous: series of slender prisms Dendritic Dodecahedral Euhedral Mamillary: rounded intersecting contours Massive: lacks crystal shape Octohedral Prismatic: Collumnar, there is a substantial thickness to the collumns scalenohedron: A six-sided pyramid with unequal sides Striations: Growth lines of the crystal face. Tabular: short stubby crystals

Answer 34

This is a method used to produce laser grade corundum, chrysoberyl, YAG (yitrium aluminum garnet), and GGG. The idea is that there is a tub of melted solution and a seed crystal is placed at the surface where it nucleates a crystal. This is very slowly pulled upwards to form a boule.

Answer 35

This is the concept of having molten materials that are slowly cooled to form a crystal. This includes the Verneuil flame-fusion, zone melting, crystal pulling, and skull melting processes.

Answer 36

This involves having either a flux or hydrothermal solution that enables the reactents to be dissolved. This is then perturbed into instability (primarily by lowering P/T) to promote crystallization.

Answer 37

SWUV: zirconia is yellow to dull orange. zircon is inert LWUV: same, slightly weaker. Zircon is brown-yellow

Answer 38

a=b=c and meet at 90^o Displays the highest degree of symmetry (three four fold rotational, four three fold, 4 mirror planes) Gems: Diamond, fluorite, garnet, spinel, pyrite

Answer 39

These are workers who transform a rough stone into the mold for a gem.

Answer 40

Chemical vapour deposition growth practically forms polysynthetic diamonds by punping inert gases and diamonds gas into a chamber

Answer 41

Customer must want the stone for some reason. Commonly this includes Want to be appreciated by others (gifts) Fashions/seasons Social customs: birthstones, royalty/celebrity Myths and Legends: Metaphysics Ethical considerations

Answer 42

All crystals can show directional hardness although it is less obvious among some species, kyanite is one of the most obvious. Note: Diamonds's anisotropy is why it is able to be polished.

Answer 43

SWUV: generally weak LWUV: variable, oftentimes blue

Answer 44

There are independent scales for color and clarity that are **subjectively** graded.

Answer 45

This is the process of fashioning and polishing a diamond

Answer 46

Ore is usually put into a SAG mill and can be sorted using x-ray fluorescence or because they are non-polar they stick to a grease covered belt.

Answer 47

Generally diamond types are a function of impurities and vacancies that give them semi-diagnostic properties. type 1 diamonds deal with nitrogen type 2 diamonds do not have nitrogen

Answer 48

This uses UV fluorescence to identify diamond types

Answer 49

These are either the result of numerous inclusions (Carbon), treatment, or extremely high concentrations of nitrogen.

Answer 50

This is due to the plastic deformation of diamonds that causes a unit step shift and unalignment of the atoms. It occurs in high shear enviroments.

Answer 51

This is from radiation defects creating lattice vacancies that emit green light upon excitation.

Answer 52

This is the collusion of nitrogen, hydrogen, and nickel.

Answer 53

These are thought to be colored due to deformation and only come from the Argyle Mine in Australia. Some are thought to have manganese impurities.

Answer 54

This is when there are nitrogen atoms dispersed throughout the structure. It produces a "Canary Yellow" color.

Answer 55

These diamonds contain boron which allows them to conduct electricity and create a blue to blue-grey coloration.

Answer 56

This is a loupe with two polarizers in opposite directions that enable a person to have the stone's pleochroic character exemplified. Stones must be colored and doubly refractive. Report resulting colors and intensity. (trichroism is only seen in biaxial materials)

Answer 57

Adamantine (diamond only) Sub adamantine: zircon Bright vitreous: Corundum vitreous: glass Dull vitreous: malachite Resinous: Amber Waxy: turquoise Metallic: hematite

Answer 58

Synthetic opal tends to have a collumnar structure and polygons of light reflection it is also more porous and does not phosphoresces green like most natural opals after exposed to LWUV

Answer 59

CIBJO helps to advise and provide a confederation of similarily interested individuals, organizations, and companies FTC has a jewelry guide about how to properly label gems and jewelry

Answer 60

Glass only fluoresces in SWUV

Answer 61

This describes all anisotropic (biaxial) materials where an incident ray is split into more than one ray upon entering the material. This is the reason for "doubling" of images, like optical calcite.

Answer 62

This is a term that relates to a gems ability to resist change due to light, acid, oil, or heat, (stability), the hardness, and the toughness of the gem.

Answer 63

This can be done on any permeable material and involves soaking a material in a liquid to improve the color consistency throughout a stone. It is common to do after bleaching

Answer 64

look for sharp changes in color in cracks/veins. The absorption spectrum of the material will match to dye and not the stone itself. They may also show discrete patches of fluorescence/non-flourescence. Acetone test: DESTRUCTIVE use with caution but a swab with acetone will stain most organic dyes

Answer 65

This is an energy dispersive x-ray fluorescence spectrometer. It is a non-destructive quantitative bulk chemical analysis technique with the limitation that it can only detect heavier elements meaning those with higher atomic numbers. Pearls: Detects Mn in freshwater pearls and Sr in saltwater pearls. Cannot seperate natural and cultured pearls

Answer 66

These are long squirly inclusions that are indicative of glass.

Answer 67

An emission line in a spectrum will appear as a high energy peak in a plot of Intensity vs. wavelength

Answer 68

A crystal which has a mirror image habits and optical characteristics occurring both in right and left handed forms.

Answer 69

Calcite CaCO₃ Malachite Cu₂(OH)₂CO₃ Rhodochrosite MnCO₃

Answer 70

Acicular: rutilated quartz Bipyrimidal: Sapphires Botryoidal/globular: chalcedony or hematite columnar/fibrous: kyanite, calcite dendritic: moss agate dodecahedral: garnet euhedral: diamond, spinel, quartz Mamillary: malachite massive: rose quartz octohedral: diamond, spinel prismatic: tourmaline, quartz, zircon scelenohedron: Sapphire Striations: tourmaline, quartz, pyrites Tabular: Ruby

Answer 71

Beryl (aquamarine), benitoite, cordierite, tourmaline

Answer 72

Feldspar, Sodalite

Answer 73

Single-Chain (pyroxenes): Jade, rhodonite Double chain: Amphiboles

Answer 74

Olivine, Garnets, the aluminosilicate series (sillimanite, andalusite, and kyanite), topaz, zircon, staurolite

Answer 75

Micas, Chlorite

Answer 76

Zoisite (Epidote), Vesuvianite (Idocrase)

Answer 77

There would be two shadow edges but only one moves. This shows it is double refractive and uniaxial.

Answer 78

The table is the top of the facet. The girdle is the vertical band around the stone's midsection that is used to keep the stone in its setting The cutlet is a little flat part at the bottom tip of the stone that helps prevent brittle fractures and reduces cut imperfections. The crown is the part of the stone above the girdle.

Answer 79

This is a type of inclusion that represents a "healed" fracture. It looks like a fracture but it is not a plane that has cohesion it is generally less sharp.

Answer 80

Ferrous (Fe²⁺) causes the green of peridot and red of almandine Ferric iron (Fe³⁺) causes the green color in sapphire Iron is also responsible for the blue colors of aquamarine and blue spinel

Answer 81

This is the emission of visible light due to excitation of atoms due to higher energy light interference. It is caused by short wavelength light (E=k(1/lambda))

Answer 82

This is used for emerald, ruby, sapphire, spinel, and alexandrite It has a series of strung seed crystals in a platinum container with different reactants above and below the seed crystals and a flux in the center. This is heated so the reactants go into solution and precipitate onto the seed crystals. This is identified by the presence of "wispy veils" not "fingerprints" in emeralds and corondum

Answer 83

Hue: secondary vs. primary (eg Purplish-blue) Tone: Light or dark (eg light blue) Saturation: Color intensity; deep, bright, vivid, pale Consistency of Color: Even, patchy, zoned, bi-colored, parti-colored

Answer 84

Basal: Parallel to the pinacoid. 1 direction of cleavage. Octohedral: Parallel to octohedral faces (flourite, grows cubic) Prismatic: Parallel to prism faces. This has four directions of cleavage. Rhombohedral: Parallel to the rhomb faces (calcite). This is three directions of cleavage.

Answer 85

This is an inclusion that represents a random, non-directional break within a stone.

Answer 86

This is a broad category that primarily describes how something breaks that is not on a cleavage plane. It is conchoidal, hackly, splintery, or smooth (diamonds)

Answer 87

conchoidial: quartz, obsidian hackly: gold, silver, platinum splintery: kyanite, serpentine uneven: ammolite, chrysocolla Granular: jade, jadeite, lapis lazuli smooth/even: Basal topaz

Answer 88

This is the filling process that involves filling fractures with polymers or oils to remove the optical effects and improve durability.

Answer 89

This is done through using a high RI glass. Look for a characteristic color flash (pink to green) and occasionally frisbee like bubbles form in the cracks.

Answer 90

Look for discrete planes of blue-yellow iridescence and bubbles/clouds (epoxy)

Answer 91

Fourier transform infrared spectrometer This is useful to identify diamond types, synthetic quartz, turquoise stabilization, and emerald determinations.

Answer 92

Atom: This is the smallest unit of ordinary matter that forms a chemical element. It is composed of particles. Proton: Positive particles within an atom Electron: Negative particles within an atom Neutron: ~same mass as a proton but without an electric charge

Answer 93

This is the process involved with producing "synthetic" opal (truly a simulent). It involves suspending a gel of silica spherules that slowly settle and produce the simulent.

Answer 94

This is broken into coloured stone mining: ASM (Myanmar, Brazil, Sri Lanka, and Madagascgar) and Diamonds: LSM (Canada and Russia) divided by kimberlites and lamprolites

Answer 95

The study of gems from origin to jewelry, including the study and identification of gemstones and their treatments.

Answer 96

This refers to when a gem substitute does not have the same structure as the original gem.

Answer 97

Cost Vs. Demand Durability, rarity, beauty at time=t properly identified and treatments considered. 4 C's: Cut, Carat weight, Color, Clarity 5th C: Cost

Answer 98

Any material that is used for adornment or decoration especially when cut nad polished. This includes rough or cut minerals chosen for their beauty and durability that have been cut and polished specifically for adornment. It also includes ornamental rock, biogenic/organic material, or artificial/synthetic.

Answer 99

This is the group that sells the cut and polished stones to jewelersand retailers

Answer 100

Generally the gemstones start at the production (mining or synthetic). 2. ) they are traded between rough dealers, cutters, and treaters 3. ) they are traded between cut dealers and manufacturers 4. ) retail 5. ) customer 6. ) secondary market/auctions

Answer 101

This refers to a suite of potential alterations that is defined as the process of artificially altering and improving the appearance or properties of gem materials. It ought to be disclosed by sellers.

Answer 102

Generally, you cut off the upper point. Then it is **Butted** which is rounding the stone. Then it is **Faceted** which gives the stone a few rough faces. This is finished by **Brillianteering** which includes adding all of the small faces and polishing.

Answer 103

Law of original horizontality: Rocks have a tendency to be created in horizontal layers Law of Superposition: Older rocks have a tendency to be at the base of the formation under review. Law of inclusions: This says that xenoliths/clasts are older than the layer they are found within. Cross-Cutting: To be cross-cut the layer has to be older than the intrusion.

Answer 104

Harder gems are less likely to lose lust after being polished and will polish better.

Answer 105

The ability of a material to resist scratching and abrasion, measured on the Moh's scale of hardness. Look at how sharp the facets are and how deep scratches are to indicate relative hardness of a stone. Hardness testing is **destructive** so always work from soft to hard testing in places that are not readily visible. Do not use a diamond point for testing.

Answer 106

Heat treated amber removes the impurities and clouds in the stone but can leave a burnt crust on the edges and stress spangles.

Answer 107

At a variety of temperatures it can enhance color, remove inclusions, create inclusions, remove color, and create/remove chatoyancy.

Answer 108

This is a suite of treatments most commonly used to remove or even out color through changing the valency of transition metals, diffusing materials, or dehydration. It is also used to exsolve or dissolve inclusions (rutile in qtz). It can also be used to create fractures to mimic natural stones or increase the effects of dye.

Answer 109

This is used to improve the color of the stone and involves the reaction of various inclusions and elements within a stone changing valency or bonding.

Answer 110

In the dark blue sapphires heating shifts Fe²⁺ to Fe³⁺ + e^- This lightens the stone. In Light blue sapphire there is low ferrous iron and potentially Ti⁴⁺ which creates a reducing enviroment to produce more ferrous iron and enhancing the blue color.

Answer 111

This is the idea that heating causes valency shifts that can be reversed through irradiation. This includes beryl, quartz, and topaz

Answer 112

Aquamarine can be heated to become more blue by reducing beryllium and irridated to oxidize beryllium to form yellow helidor.

Answer 113

Various irridation at different temperatures can create carbon vacancies, transform carbon to nitrogen, and create nitrogen isotopes that produce distinctive spectra trackable with raman.

Answer 114

This system has 6 equal faces parallel to the z-axis making it have 6 fold symmetry. a=b/=c α= 120^o β= γ= 90^o This is also said as having 4 axis (three in the x-y plane at 120 degrees and a z axis) Gem Examples: Beryl (heliodor, aquamarines, morganite, emerald), apatite, taaffeite

Answer 115

Contact twins (calcite) Brazil and dauphine twins (qtz interpenetration twins) Japan (qtz contact twin)

Answer 116

This was developed in the 1950's for diamonds and principally using a triaxial compression machine to compress a heated vessel of carbon to produce diamonds. They two main machines are called the belt and BARS

Answer 117

These are radiating fibers that nucleate from one spot within demantoid garnets.

Answer 118

Many states have legislation that limits the transport of ivory and fossil ivory across state bounds making it illegal to purchase unless a state resident.

Answer 119

Rotate the stone until iridescence is seen Orient the conoscope over this iridescence to see the interference figure.

Answer 120

This produces yellow to brownish yellow, type Ib yellow diamonds Blue diamonds Type IIb + Type Ib Greeb Type IIb + Ib Colorless Type IIa

Answer 121

This is used on diamonds to alter the color centres

Answer 122

This places seed crystals (plates) in an autoclave with reactants and water. This creates a supersaturated solution that is cooled to produce synthetic corundum, emerald, beryl, and quartz

Answer 123

The heating of meteoric, sea, or magamatic fluids to transfer and deposit elements through subsurface "plumbing"

Answer 124

They will have radiating circles from the spinning and progressive stepwise changes in reactant addition.

Answer 125

They will often have bubbles at the junction, feathers or other inclusions with abrupt ends at the interface. Generally look at the side to ID layers, different wear along the facets, sharp changes in luster or color, and bubbles in adhesives.

Answer 126

Most commonly this includes moissanite and cubic zirconia. Both are doubly refractive so look at the setting and see if it doubles. Alternatively, you can place the stone over a black line and if it is not a straight line it is CZ or moissanite. Look for a sloppy cut Look for unpolished corners. Only diamonds will have tiny parts that are left natural to maximize the carat weight.

Answer 127

Occasional "breadcrumbs" of metal flux hour glass colour zoning stronger reaction to SWUV than to LWUV Attracted to a strong REE magnet

Answer 128

They oftentimes have small chevron or zig-zag patterns in their lattice although they are difficult to distinguish.

Answer 129

It was originally only a material found in meteorites but is doubly refreactive and if set in jewelry you can look through the base to see if it doubles the image. Diamond is isometric so this will not occur.

Answer 130

These are gems that have transition metals integrated into their lattice to be 'self colored'

Answer 131

These are natural or artificial materials that are used to imitate the effect, colour and appearence of other natural gem materials without having equivalent chemical and physical properties

Answer 132

Primarily alluvial deposits of garnet, diamond, olivine, and other resilient gems.

Answer 133

This is treating a stone with wax, oil, and other substances to either improve appearance, lustre, transperency, or durability. It is common in stones that may otherwise be porous or have many fractures like turquoise, jadeite, and lapis lazuli. This substance may also be colored making it a dyeing and consolidating process.

Answer 134

This is a directional fracture within a stone.

Answer 135

This refers to internal cracks/fractures that can or cannot reach the surface.

Answer 136

This is the result of anisotropic minerals e and o rays constructively interfering when exiting the crystal. The two add like vectors and this changes the speed and %transmission of the resultant light. This is proportional to specific mineral properties, thickness, and the light source.

Answer 137

Inclusions, color zoning, feathers, and cleavage lines

Answer 138

Platelets of hematite cause sunstone's shimmer. Copper within glass creates "goldstone" Green mica spangles cause aventurine quartz.

Answer 139

This is caused by thin layers of heterogeneous solid or liquids within a material. This commonly includes exsolved feldspar (labradorite), layers of agate (fire agate), aragonite in pearl. The different layers reflect light differently and creates the shimmering effects we see due to wave constructive/destructive interference. This is what creates the iridescence.

Answer 140

1. ) high-energy neutron rays from a nuclear reactor 2. ) streams of electrons produced by an accelerator 3. ) gamma rays produced by a radioisotope, typically Co⁶⁰

Answer 141

Spinel (octohedral contact twins) Iron cross (2 pyritohedrons rotated 45^o apart) Inerprenetration along {111} fluorite. This adds three fold symmetry.

Answer 142

This is when there is a synonymous structure/lattice of a material but there are different elements interchanged within minerals. For example, the cation site in garnet. This is also called isomorphism.

Answer 143

One of two or more species of atoms of a chemical element with the same atomic number but differing masses and properties

Answer 144

Mineral properties that are non-directional. Isotropic minerals are extinct in XPL and light travels at the same speed through every direction through the material. It is a property that arises due to symmetry. Glass, gases, amorphous solids, isometric minerals, and most liquids are isotropic materials.

Answer 145

This is a type of giant tooth. It can be simulated with sperm whale teeth, walrus tusk/teeth, narwhal, bear, elk, crocodile, hippopotamus, warthog teeth.

Answer 146

This is a type of petrified wood or petrified coal.

Answer 147

This is the process of sending a cut stone to a factory to be faceted and polished

Answer 148

This uses a laser to not drill into a stone but to heat it to cause a surface reaching fracture that is used to remove a dark inclusion with acid.

Answer 149

Laser ablated-Inductively Coupled Plasma-Mass Spectroscopy This is a very expensive tool that vaporizes a tiny portion of material to be quantitively analyzed by the proportions of oxides present. It is ideal for low atomic number elements and for trace elements.

Answer 150

This is the art of cutting and polishing gem materials that are not diamond

Answer 151

This is used on diamonds to reduce or remove dark inclusions. It involves using a laser to drill into a diamond until the inclusion is met. This is then dissolved to remove the unpleasant inclusion

Answer 152

Intrinsic Defects: Vacancies (missing an atom), edge/loop dislocations (when there is a terminated chain of atoms) Extrinsic Defects: Interstitial impurity atoms (random heterogeneous atoms), precipitate of impurity atoms (a chunk of impurity), Substitutional impurity atom (substitution unlike the structure)

Answer 153

Nodes are collections of atoms within the lattice. They represent elements.

Answer 154

Laser induced breakdown spectroscopy unit This is a type of ICP-MS unit that vaporizes a tiny portion of a stone to identify treated corundum.

Answer 155

These are partially healed tension cracks around a small cavity or pore in peridot

Answer 156

This is the emission of "cold" non-incandescent visible light. It is all emission of light from a substance. fluorescence is a type of luminescence.

Answer 157

This is a term that describes the _surface_ reflectiveness/gemminess. This is influenced by hardness, reflective index (the best test for lustre), polish quality, and surface quality. It is a property that is proportional to durability.

Answer 158

Mammoth lines are at ~90^o elephants are greater than 90^o towards the outer edge of the tusk.

Answer 159

This is a form of polysynthetic twinning on the {001} of orthoclase

Answer 160

These are groups of mineral series and end-members

Answer 161

Supergroups: Include 3 or more groups of minerals Groups: Includes several minerals Species/End-Members: Individual mineral compositions Variety: End-members that may have specific trace elements that alter their appearence.

Answer 162

These are naturally occurring mineral-like substances that lack crystalline structures. These include obsidian and opal.

Answer 163

A naturally occurring inorganic crystalline solid of fixed limits of chemical composition and physical properties composed of 2+ elements. 3+ minerals make rocks

Answer 164

This is the most common diamond cut that is seen very often.

Answer 165

a/=b/=c α= γ= 90^o β\>90^o This system is characterized by being an elongated parallelogram and has 2-fold rotational axis and/or 1 mirror plane. Gem examples: Feldspar (K-spar only; moonstone), malachite, azurite, clinopyroxenes (diopside and jadeite), staurolite, sphene/titanite, and spodumene (kunzite).

Answer 166

Manebach law, carlsbad law, braveno law, swallow tail twins.

Answer 167

This is the hexagonal aragonite layers in a pearl. They are interlayered with an organic layer of conchiolin and create the iridescence

Answer 168

These are materials that have been formed by nature without human interference or modification outside of fashioning

Answer 169

This will only show at a maximum three isogyres. When oriented in this direction they will be extinct in 360 rotations in XPL.

Answer 170

masonry bit: 8.5 Steel nail: 6.5 Knife/glass plate: 5.5 Copper penny: 3.5 Fingernail: 2.5

Answer 171

1. ) Start with general inspection. Identify color, transparency, heft, crystal forms, and other noteworthy characteristics. 2. ) Use the loupe to ID inclusions, lustre sharpness of facets, cleavage, fracture, and other noteworthy characteristics. Rest the loupe on your cheek bone and hold the stone at an equidistance from your loupe as the loupe is from your eye. 3. ) Further inspection? Microscope.

Answer 172

Faceted: sharp defined edges Cabochon cuts, rounded domes Carvings: these are not defined by having a "base" Cameo: These are a carving extruding from a base intaglio: this is a carving intruding into a stone

Answer 173

This is the axis within a crystal where double refraction does not occur. Uniaxial crystals have one direction that double refraction does not occur. Biaxial materials have two.

Answer 174

One of the optic axes is perpendicular to the stage and there is a partial isogyre.

Answer 175

This is a flash figure and it represents when one of the privileged directions is parallel to the incident rays. This has the maximum level of interference.

Answer 176

This is a group of phenomena that articulate how light interacts with stones Asterism: This is chatoyancy with more than one line that creates a star or some other shape. Chatoyancy is cat's eye. Play of color: This is the multi-colored stones that are common with opals Iridescence: This is the multi-colored reflection of light due to thin films of material being present. Internal Reflections/Inclusions: These are for internal objects and different substances within a material. Scattering: This is light scatter due to irregular particles. It creates a sky-blue color with clouds. Color Change: This is idea that some stones change color under different light sources.

Answer 177

These are doubly refractive materials that shift between extinct and not extinct 4 times through a 360^o rotation

Answer 178

Carbon-based mineraloids, jet, pearl, amber, ivory, coral. Pearls are the only gem explicitly unaltered.

Answer 179

a/=b/=c α= β= γ=90^o Gems: Olivine (peridot), topaz, chrysoberyl, cordierite (iolite), tanzanite Symmetry Elements: three 2-fold rotational axis and/or 3 mirror planes

Answer 180

Two shadow lines move. This shows the material is doubly refractive, biaxial.

Answer 181

Cyclical twins (aragonite) Interpenetration twins (staurolite)

Answer 182

Red diamonds have phosphorous or deformations Purple diamonds have H⁺ Green diamonds have been irridated Black diamonds have carbon or are deep mantle diamonds (metals) pink diamonds (Argyle mine) have dislocations brown diamonds have dislocations that can be treated via HPHT

Answer 183

Chrysoberyl: BeAl₂O₄ Corundum: Al₂O₃ Quartz: SiO₂ Spinel: MgO\*Al₂O₃

Answer 184

This is a term that refers to minerals growing with parallel edges/faces. This is a mineral cluster not a twin.

Answer 185

This is not a twinning phenomena but describes with all faces of a crystal are formed in contact with the adjacent crystal cluster.

Answer 186

This is "psuedo-cleavage" that occurs at discrete intervals but are not on the weakest planes.

Answer 187

This is the result of a mollusk covering something with nacre and organic layers of conchiolin

Answer 188

ONLY Freshwater pearls fluoresce Saltwater pearls with a thin nacre film around a freshwater nucleas may fluoresce. Conch pearls are purple in x-ray radiation. Pearls are oftentimes scanned/x-rayed to look at each individual nacre layer and identify if there is a bead at the center of the pearl.

Answer 189

Look in the drill hole for a nucleas and/or banding from a shell. Use LWUV, cultured have a green tint, Cortez Sea pearls are bright red, natural have a green tint, and general size/shape.

Answer 190

Feldspars, quartz, beryl, tourmaline, topaz, and zircon

Answer 191

This is when pressure distorts the lattice of a crystal slightly to create a dipole that is used as an electric charge. It occurs in trigonal minerals.

Answer 192

This is a form of incipiatte fracture around inclusions.

Answer 193

[M+](PO4)x Character: Soft and effervescent Apatite: Ca5(F,Cl)(PO4)3 Turquoise: CuAl₆(PO₄)₄(OH)₈\*4H₂0 -note: Phosphates can easily replace one another. Turquoise after apatite within fossils and mineral deposits.

Answer 194

This is a type of luminescence when materials radiates after being irridated by a high energy source. Phospherescence occurs after the high energy light is removed. In comparison fluorescence requires the stone is continually irridated to release the light.

Answer 195

Habit, luster, color (colorless), heft, prisms, terminations, fracture, cleavage, crystal system, transparency.

Answer 196

This is any distinguishing property with a physical specimen that can used to ID the object.

Answer 197

A pinacoid is a pair of planes that are either "side pinacoids" (parallel to c-axis) or basal (in the a-b plane)

Answer 198

This is light that is polarized in two directions.

Answer 199

Plane lattices are in 2d. Space lattices are 3d.

Answer 200

Plastic will have chips or is flaky in certain areas.

Answer 201

This is because of different radii of stacked spheres/globules of SiO₂ that are creating opal. The gaps between spheres cause diffraction and the resultant colors. This is similar to what occurs in a rainbow. The larger the gaps the larger the range of colors.

Answer 202

This is a term for when a mineral that shows multiple colors dependent on the orientation/transmission of light. It is best seen down the OA where the fast and slow directions create different colors dependent on which polarity of light is able to travel through. There will no color change if the OA is perpendicular to the stage. Isotropic minerals will not be pleochroic. Report pleochroism through terms of intensity and using the dichroscope (weak, moderate, strong).

Answer 203

100 points=1 carat 50 points=.5 carat

Answer 204

This is a light transmitting device that can be used to test the optics of rough, faceted, or carved materials. It has two polarizers; the material goes between these two polarizers to be observed. The two polarizers are at 90^o from one another creating XPL view or the two rays are said to be plane polarized. It is not diagnostic but helps to classify and narrow down the search.

Answer 205

Dark through a full rotation = optically isotropic, singly refractive, amorphous or isotropic. Light and dark 4x in a full rotation = optically anisotropic and Doubly Refractive Light through a full rotation = polycrystalline Patchy light and dark through a full rotation = singly refractive with strain. This is anomalous double refraction.

Answer 206

Place the stone on the rotating stage and rotate the stage in 360 degree rotations. re-orient the stone and repeat. Report results Singly refractive = extinct always=isotropic doubly refractive= 4x extinct = anisotropic fully illuminated always = polycrystalline anomalous extinction = strain = polycrystalline or amorphous with strain

Answer 207

Unpolarized light has components in all directions. Polarized light is constrained to a plane. Reflected rays are polar parallel to the reflecting surface and refracted rays are partially polarized parallel normal to the refracted ray.

Answer 208

Aggregates of randomly oriented small crystals or crystal fibers which need magnification to identify. Examples: Jadeite, nephrite, chalcedony, turquoise They are fully illuminated in the polariscope

Answer 209

This is the aggregate of randomly oriented small/micro crystals/fibers. Examples include jadeite, nephrite, chalcedony, or turquoise.

Answer 210

These materials will never go extinct through a 360^o rotation.

Answer 211

Chemically synonymous compositions with differing structures

Answer 212

Saltwater=~10\*freshwater natural=~100\*cultured

Answer 213

This is when crystals that are heated show electrical properties. This is why tourmaline in show cabinets attract dust. It is fundamentally caused by the heat causing charge diapoles in the crystals forming partial positive and partial negative zones.

Answer 214

Rutile (brown=Brazil, Red=NC), dumortierite (blue acicular needles from Brazil), hematite, brookite (silky grey lines), petroleum, asbestos replaced by quartz (tigers eye), mica (aventurine), moss agate (epidote)

Answer 215

This is the effect of shooting a laser at a substance and some of the photons scatter. Some photons interact with the electrons within the bonds of the material to excite electrons. Upon returning to a ground state this will create "scattering" characteristic to the material. This is used to identify the material.

Answer 216

Generally a more rigid structure (like diamond) produces very sharp peaks. Amorphous materials produce broad peaks.

Answer 217

LAsers are used because they uniquely have enough energy to excite electrons. The return wavelength from the electrons is the same regardless of the source. The intensity of peaks does change with source wavelength though.

Answer 218

Geographic Rarity: This is determined by how widespread the variety is among localles. Tanzanite is geographically rare Historic rarity: Historic mines produce rare gems. Burma rubys, Kashmir sapphires Quality related rareness: Abundant gems that are low quality vs rare gems at high quality (diamond) Specific color or saturation: Gem-specific rarities like amethyst with a red/blue flash

Answer 219

This is the process of taking pieces of a material and re-bonding them together. Amber can be reconstructed by heating many pieces to 200 C Look for sharp boundaries and interesting feathers or bubbles.

Answer 220

These are artificial materials made by bonding or fusing materials into a singular gem.

Answer 221

These are very unreliable reflectance measures.

Answer 222

No refraction occurs

Answer 223

This is defined as n=C/C_m this is the ratio of the speed of light in a vaccum to the speed of light in the material of interest. n\>1

Answer 224

A "table" of very high RI material is used to place the flat, polished, side of a gem. Light is passed up at an angle through the table onto the stone. Because the gems's RI is less than that of the table some of the material is reflected back and the boundary between the totally reflected light and the shadowy, partially reflected light is the shadow edge. It principally reflects light and then splits the emergent o and e rays to identify the birefringence of a stone, uniaxial/biaxial character, and if it is positive/negative. It is a semi-diagnostic test.

Answer 225

1. ) remove the polarizing filter (if present) 2. ) Prepare with the refractometer oil by placing a small drop on the glass table. 3. ) slide a suitable facet gently over the drop. Generally, place the largest face/facet downwards. 4. ) Keep the stone centered and look into the eyepiece at the shadow edge. 5. ) Rotate the stone. IF no shadow edge moves the stone is ISOTROPIC (singly refractive). IF two shadow edges (seen as a partially illuminated area of the scale) move the stone is BIAXIAL. If one moves it is UNIAXIAL. 6. ) Use the max-min to find the birefringence and report the highest values for RI.

Answer 226

This is the ratio of the weight of a material to the weight of another material of equivalent volume. In comparison to SG this does not have to be compared to water, although that is commonly the case.

Answer 227

Materials can "cut-off" at one end of the spectrum. There can be bright emission lines Thick, thin, fine lines. There are "three zones" of color. Blue, yellow, and red.

Answer 228

This is the interface of the jewelry industry and the public. It is increasingly moving towards online sales.

Answer 229

sed rocks to meta or weathering. meta to magma, erosion. ig to melt, meta, weathering.

Answer 230

These are things composed of 3 or more minerals.

Answer 231

These are dealers selling stones most proximal to the mines. This is also the locale where the greatest amount of synthetics are integrated into the supply chain.

Answer 232

Natural: Rounded back (increases weight), off-center star, slightly fuzzy arms Synthetic: flat back, centered star, the reflection seems to be "sitting" on the stone surface.

Answer 233

This is done using a leaded glass that show blue to golden flashes an bubbles. The glass may be a significant proportion of the stone's volume.

Answer 234

This is caused by misalignments in the crystal structure due to inclusions (in moonstone it is albite and causes adulescence) The scattered transmitted light is reddish/pink. The top/sides that are reflected are sky blue.

Answer 235

This is the resell market and includes pawn shops, auctions, and consignment (increasingly popular)

Answer 236

This is the property of certain elements (primarily transition metals) to absorb most wavelengths of light and the reflected wavelengths are those we observe.

Answer 237

This is the boundary between to the totally reflected light and the partially reflected light used to indicate RI. The other line (@ 1.79 or 1.81) is the refractometer fluid used to create a contact between the gem and the table.

Answer 238

Island/Nesosilicates: Characterized by individual tetrahedra of silicate Paired/Sorosilicate: Tetrahedra are linked in pairs Inosilicates: BOTH single-chain (pyroxenes) and double-chain (amphiboles) silicates Ring/Cyclosilicates: Complex ring "sheets" Sheet/phyllosilicates: Complete sheets of connected tetrahedra often forming hexagons connected to three other hexagons Framework/network silicates: Connectivity of 4

Answer 239

Silicic acid with metal [M⁺](SiO_y)_x Very hard and durable

Answer 240

Usually a very fine rutile inclusion that may cause a hazy appearance in the stone, most often seen in corundum.

Answer 241

These are optically isotropic materials. They are singly refractive.

Answer 242

This is used to principally produce cubic zirconia. It involves having a porous shell aka "skull" filled with seed crystals at the base and the reactents above. This is then heated with a coil that is slowly raised allowing the base to slowly cool and form CZ.

Answer 243

This says that n_i \*sin(i)= n_r sin(r) where i is the angle from the incident ray to the normal and r is the angle from the refracted ray to the normal. Note: the reflected ray is at i too.

Answer 244

These are the white radiating patterns in obsidian

Answer 245

This is a triplet where the top is spinel, then there is a layer of emerald and the base is glass

Answer 246

α= angle between B and C axis β= angle between the A and C axis γ= angle between the A and B axis

Answer 247

Specific gravity is defined by the ratio of the mass of material in air to the mass of displaced fluid (H₂O @STP) of equal volume. In practice it is wt_s(air)/(wt_s(air)-wt_s(water)). This is _hydrostatic weighing_

Answer 248

This requires white light that can be split into the whole visible spectrum. This light is sent through a crystal and the viewer is able to see only the transmitted wavelengths. The dark areas show areas where the gemstone has absorbed the light. The emission spectra is characteristic of particular minerals/materials although the test is not diagnostic it can help narrow coloring elements.

Answer 249

Option 1: fix the stone to a source of white light using putty. Look through the spectroscope to see the spectrum. Make sure that the putty fully covers the light source and the room is dark. Option 2: place the stone on a black or dark background. "Bounce" the light through the stone into the spectroscope. Report emission lines, cut offs, thin, and thick lines within their given color range.

Answer 250

This is the science of analyzing the interaction of light with a material, either visually, or mathematic analysis. For our interests spectroscopy is related to the emission spectrum of minerals.

Answer 251

Spinel is cubic and red. It commonly forms macles and has triangular pits on the pyramid faces.

Answer 252

This is the ability of a stone to resist alteration due to light, heat, or chemicals.

Answer 253

This is common with extremely porous materials that are impregnated with polymer resins to increase durability.

Answer 254

There are two principle steps, nucleation and crystal growth. Nucleation refers to the physical process of achieving the correct orientation of materials that equates to the crystal structure. Crystal growth refers to the chemical process of the material growing based on the nucleated crystal. The rate and extent is related to the amount of reactants available and the environmental conditions which growth is initiated. It is generally crystallization from a melt or solution.

Answer 255

This is a subjective measure of a stone that changes with place and time but is generally dependent on style of cut and shape, color, transperency, luster, optical effects. It is ultimately determined by how the stone interacts with light.

Answer 256

This is a process for producing synthetic moissanite (gem grade silicon carbide) It involves sublimating graphite and Si C powder at 2300^oC and sucking it into an Argon atmosphere where at the base of the vessel it is 2200^oC and a seed crystal grows into a boule.

Answer 257

This is polysynthetic twinning common in gypsum along the {100} plane. It is parallel to the a-axis.

Answer 258

SWUV can cause burns. Do not stare into any UV light and do not expose yourself to SWUV to avoid sunburns.

Answer 259

Iron pyrite

Answer 260

These are a sub-section of artificial materials that aim to mimic or replicate their natural counterparts. They have physical and chemical unity with their natural counterparts but if considered path dependent do not follow a natural path.

Answer 261

SWUV: it is chalky blue/green LWUV: it is inert

Answer 262

Synthetic opals will have the colors "stacked" in a cross section of the stone. This is because the stone is made by allowing sphereoles of silicon dioxide fall.

Answer 263

This primarily occurs in large factories in either China or Russia

Answer 264

This is an ivory simulant made from the tagua nut, a type of palm nut.

Answer 265

Note: the isogyres show the principal planes that the o and e rays travel through.

Answer 266

Quality: Perfect, distinct, good, fair, poor Difficulty: easy, hard, difficult. Describes how hard something must be hit to cleave.

Answer 267

a=b/=c α=β=γ=90^o This is a rectangular prism and the system has a single 4-fold rotational axis. Gems: Zircon, idocrase, rutile, wulfenite, scapolite

Answer 268

Cyclical Contact Twins like cassiterite and rutile. Oftentimes on the {011} plane.

Answer 269

This is a HPHT method for diamond synthesis where diamond powder is set within a metallic flux (iron or nickel) and the capsule is subjected to extreme heat and pressure. They use a seed diamond at the base and the new crystal forms dependent on the seed crystallographic orientation, P, and T

Answer 270

Ti: blue V: green+pink (emerald) Cr: red+green (ruby, emerald, alexandrite) Mn: pink (rhodochrosite) Fe: green, blue, red, yellow Co: blue (spinel) Ni: green (turquoise) Cu: blue, green

Answer 271

10: daimond 9: corondum 8: topaz 7: quartz 6: orthoclase 5: apatite 4: fluorite 3: calcite 2: gypsum 1: talc

Answer 272

This is important for diamond distinction. Generally, most stones are very poor conductors but diamond is a very high thermal conductor and moissanite is too. The two are differentiated because moissanite is electrically conductive and diamond is not.

Answer 273

Metapelites: These are metamorphosed clay rocks Metacarbonates: Metamorphosed carbonates Metabasalts: Metamorphosed basalts

Answer 274

Hypothermal: These are the highest P and T hydrothermal deposits. 300-500 celsius Mesothermal: Intermediate depths and pressures 200-300C Epithermal: Shallowest depths and low T 50-200C

Answer 275

stripes along partially healed twinning planes in quartz

Answer 276

Clear topaz can be irridated brown then heated blue. This can be further heated to be clear again or irridated to become brown again.

Answer 277

Real shell will be less sharp at the boundaries of the coloration whereas plastic will have sharp edges of coloration, non-diffusive.

Answer 278

This is the angle (i_c) of a ray where the refracted ray has r=90 so it travels along the interface of the substances and the ray of light is totally reflected back into the material. The gemological refractometer uses TIR to measure birefringence and RI.

Answer 279

This is the ability for a stone to resist fracture or cleavage. It is more related to acute stresses and not long term wear.

Answer 280

Ti: blue V: green, pink Cr: red, green Mn: Pink Fe: green, blue, red, and yellow Co: Blue Ni: Green Cu: Green, Blue

Answer 281

Transparent means that you can read through it. Translucent means that you can see through it. Opaque means that you cannot see through it.

Answer 282

This is a hexagonal inclusion in emeralds due to carbon materials that causes sectored growth.

Answer 283

This alludes to the processes of both treating the rough/cut material and the latter processes of trying to identify the treatments.

Answer 284

This is when a stone is particular prone to static charge like amber.

Answer 285

a/=b/=c α/= β/= γ/= 90^o symmetry includes a one fold rotational axis Gem examples: Feldspar (plag; sunstone and labradorite), kyanite, rhodonite, turquoise

Answer 286

Albite and Pericline twinning. This is polysynthetic twinning perpendicular to the b axis.

Answer 287

This is a subdivision of hexagonal w/ less symmetry where: a=b/=c α= 120o β= γ= 90o This is also said as having 4 axis (three in the x-y plane at 120 degrees and a z axis) and shows only three fold symmetry. Gems: tourmaline, quartz, corundum

Answer 288

These are triangular pits that appear in the octohedron faces of diamonds that are from etching during exhumation. They are in the opposite direction of the point.

Answer 289

These are in the direction of the octahedron and show a preferred habit. Ex: Spinel

Answer 290

"synthetic" turquoise: it does not have a groundmass and if placed into a groundmass as a conglomerate it is visible in a loupe Reconstructured turquoise: Composites of dust and can be ided using IR spectroscopy to detect adhesive Dyed howlite or magnesite: look for greyish marks.

Answer 291

This is when 2+ crystals grow together in a crystallographic relation that produces a symmetric shape. It has an abrupt change in the lattice continuity without changing the structural continuity. It is caused by stress or a change in P/T during growth. Twins NEVER form on a previously existing symmetry plane but do increase the symmetry.

Answer 292

1a: nitrogen is aggregated into clusters. These started as 1b but aged and diffused. They are colorless or yellow 1b: These are younger, yellow/orange diamonds, with disseminated nitrogen throughout the lattice 1aA: These are yellow diamonds with Nitrogen pairs throughout the structure. 1aB: This is when there are 4 nitrogens around a square vacancy where the corner atoms are carbon.

Answer 293

These diamonds do not have nitrogen 2a: These have no nitrogen or boron, colorless 2b: These have dissemeninated boron atoms (B⁵⁺) they are blue

Answer 294

Conchoidal: shell-like fracture with clam shell striations. Slightly concave. Ex: network silicates Hackly: Breaking along jagged irregular surfaces. Common in aggregate masses. Splintery: Long fibrous splinters Smooth/even: There are no signs of roughness. Like in diamonds

Answer 295

Synthetic gems (lab-grown diamonds) Biogenic (pearls) Minerals (Emeralds, Rubies...) Adornment Material (Rocks like Lapis Lazuli)

Answer 296

Single monophase inclusion: a single liquid or gas or solid within a mineral two-phase inclusions: more than one state of material Three phase inclusion: all three phases present.

Answer 297

Asterism: "cats eyes" Chatoyancy iridescence: labradorite dispersion/"fire": diamond Play of color: opal

Answer 298

If aligned down the c-axis then the figure will be a distinguishable cross. If the c-axis is not parallel to the light then you will see an arm of the figure. If the c-axis is perpendicular to the OA then there will be a flash figure and there will mainly be a big melatope.

Answer 299

The c-axis is parallel to the top facet in a uniaxial crystal and thus if the higher shadow edge moves up and down it is positive. If the lower RI shadow edge moves it is negative.

Answer 300

Uniaxial materials are characterized by two extreme refractive indices (n) for each wavelength. They have one optic axis and have only a max and min RI. The systems that end in 'al': trigonal, hexagonal, tetragonal

Answer 301

The unit cell is the smallest repeatable unit of nodes needed to create a lattice

Answer 302

Clean the material to remove dust, fingerprints, and other surface contaminants that can fluoresce. Place the material on a black, non-reflective surface. Do not hold it in tweezers. Minimize outside light, this is why UV cabinets are useful. Be careful to not confuse blue reflectance and blue fluorescence.

Answer 303

Ultraviolet-visible-near-infrared spectrometer This is a specialty tool primarily used for origin reports of sapphires, Paraiba tourmalines, emeralds, garnets, and to detect died materials.

Answer 304

This is a cheap, rapid, and old method for making simple oxide gems like corundum, spinel, rutile, and strontium titanate. It is basically a long tube with a dust feed at the top followed by a furnace in the middle and an air source at the base. This enables a hot kiln in the center where the dust is fed to create a boule.

Answer 305

Singly refractive Doubly refractive polycrystalline strained

Answer 306

Blue is in the upper right. Yellow is in the upper right of optically negative minerals.

Answer 307

Light turns toward the normal, closer to vertical.

Answer 308

This can appear like patches or changes in extinction dependent on the material.

Answer 309

This is often shown through one part of the crystal becoming extinct at different times than the other parts.

Answer 310

Diamond. It reflects all of the light back out to the viewer. Metallic surfaces are better at reflection but they are not gems.

Answer 311

This is a uniaxial figure with a "hole" in the center that is diagnostic of quartz.

Answer 312

It is 1/5th of a gram or the weight of one carob seed.

Answer 313

Price=wt^k where k\>1. This is idealized where in reality it is piece-wise where big notable quanta of weights change the price (eg .9 vs 1 ct)

Answer 314

It is the combination of all the colors of the visible specturm.

Answer 315

Interference figues are only seen down the C-axis in doubly refractive materials. It will help reveal whether the stone is uniaxial or biaxial (+-)

Answer 316

Stones are sold by weight. Therefore a stone with similar volume but different density will have a very different price.

Answer 317

This literally x-rays the rock for internal structure. It is used to identify pearls because they have concentric aragonite layers. It is very fast too, ~15-20 minutes

Answer 318

This is the comparison of the weight of stone retained after cutting vs. the rough weight. Generally, stones are fashioned to increase yield. It can either be said as a percent or as an absolute weight.

Answer 319

Zircon is tetragonal but often the c axis is not too long making it seem bipyramidal.

Answer 320

This used a conglomerate or sintered rod that is then heated by passing a heating coil along the rod and feeding reactent as it moves to enlarge the rod.

Answer 321

This is the fine band around the widest part of the modern round brilliant cut that is used to secure the stone in jewelry

Answer 322

This is the term referring to the part of the facet that is below the girdle in includes the lower girdle facet, pavilion main facet, and the cutlet.

Answer 323

This is the area above the girdle. It includes the table, upper girdle facet, and crown main facet.

Answer 324

Step cuts: Emerald (tapered rectangle) and Baguette cut (trapezoid) Rose cut: This is the oldest facet and it is a disco ball on the top and a flat bottom Mixed Cuts: These include more than one type of faceting style Fantasy cuts: These are particularly popular right now and create unique internal inclusions

Answer 325

These are irregular polished and tumbled stones. It also applies to irregular pearls.

Answer 326

There is medium, flat, double (rounded top and bottom), and hollow (used with garnet to increase transperency) cabochons

Answer 327

Cabochon cuts may be preferred if the stone is translucent or opaque, reveal optical effects, or to maximize the durability of softer stones.

Answer 328

These are polished or faceted materials with a hole in the middle

Answer 329

This is popular in native american jewelry and includes flat pieces of stone arranged to create unique patterns.

General Flashcards

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