GEM 230 QUIZ Flashcards
The large, stable parts of the earth’s continental crust are called A. plates. B. islands. C. shields. D. cratons.
cratons.
A loupe used for clarity grading must be corrected for chromatic and A. size distortion. B. vertical distortion. C. spherical distortion. D. depth-of-field distortion.
spherical distortion.
You should expect to pay more when you buy from a dealer A. on credit. B. in parcels. C. with cash. D. in large quantities.
on credit.
On a well-made diamond, the girdle will
A. look like a knife edge.
B. have just enough thickness to prevent chipping.
C. show its reflection when viewed through the table.
D. increase the weight of the diamond without adding to its beauty.
have just enough thickness to prevent chipping.
The three main components of the earth are the crust, mantle, and A. core. B. center. C. stratosphere. D. subduction zone.
core.
All diamond simulants rank lower than diamond in A. hardness. B. dispersion. C. fluorescence. D. specific gravity.
hardness.
Cecil Rhodes’ main competitor in his early attempts to control diamond production was A. Barney Barnato. B. Ernest Oppenheimer. C. the Diamond Trading Company. D. an independent diggers’ association.
Barney Barnato.
When the rough has a frosty or non-transparent surface, the cutter can look for inclusions by
A. X-raying the stone.
B. laser sawing the stone.
C. sawing the stone on-center.
D. polishing a window to view the interior.
polishing a window to view the interior.
Calculate the table percentage of a round brilliant with the following measurements:
Table measurements: 4.85 mm, 4.85 mm, 4.90 mm, 4.95 mm
Minimum and maximum girdle diameters: 7.95 mm, 8.07 mm
A. 59 percent
B. 60 percent
C. 61 percent
D. 63 percent
61 percent
Which one of the following clarity characteristics might be found in a synthetic diamond? A. Xenocryst B. Metallic flux C. Garnet crystal D. Diopside crystal
Metallic flux
Because the Australians believed the CSO’s marketing favored large stones over smaller ones, they
A. abandoned diamond mining.
B. discarded small, brown diamonds as mine waste.
C. turned to India for help in marketing their diamonds.
D. aggressively promoted jewelry set with their own tiny gems.
aggressively promoted jewelry set with their own tiny gems.
Synthetic diamond is a
A. natural material that looks like diamond.
B. manmade material that looks like diamond.
C. manmade material with essentially the same physical, chemical, and optical properties as natural diamond.
D. manmade material made primarily of carbon forming in a different crystal system than natural diamond.
manmade material with essentially the same physical, chemical, and optical properties as natural diamond.
Dealers who buy diamonds on memo
A. must belong to a dealers’ association.
B. can keep the stones until they are sold.
C. automatically get a 5 percent discount on the price.
D. have the opportunity to inspect stones before buying.
have the opportunity to inspect stones before buying.
The most common impurity element found in diamond is A. iron. B. boron. C. carbon. D. nitrogen.
nitrogen.
Oppenheimer’s answer to low diamond demand in the 1930s was to
A. advertise heavily.
B. reduce diamond prices.
C. shut down operations at De Beers mines.
D. stop buying diamonds from outside sources.
shut down operations at De Beers mines.
The process of polishing the star and upper and lower half facets is called A. kerfing. B. lasering. C. blocking. D. brillianteering.
brillianteering.
On emerald cuts, differences in the angles of the rows of pavilion facets cause A. wide corners. B. pavilion bulge. C. a bow-tie effect. D. a shortened culet.
pavilion bulge.
In a stone with these clarity characteristics, which would probably be the grade-setting characteristic? A. Pit B. Feather C. Pinpoint D. Extra facet
Feather
Gravity sorting separates diamonds from A. river gravels. B. lighter materials. C. heavier materials. D. indicator minerals.
lighter materials.
The flashes of color you see in a polished diamond are called A. fire. B. brilliance. C. dispersion. D. scintillation.
fire.
The devices that grip and hold a diamond for polishing are known as the A. dop and tang. B. tang and stay. C. lap and wheel. D. kerf and sharp.
dop and tang.
A commitment to reserve a portion of the resources derived from any country for the economic development of that country is called A. integration. B. beneficiation. C. Best Practices. D. the Kimberley Process.
beneficiation.
Variations in lighting and surroundings can affect a diamond’s A. RI. B. SG. C. luster. D. appearance.
appearance.
To help determine crystal directions, diamond cutters look for A. kerfs. B. needles. C. growth marks. D. included crystals.
growth marks.
A masterstone graded as whole grade represents the
A. middle of a color grade’s range.
B. least amount of color possible in that grade’s range.
C. consensus of what the trade believes that color to be. D. greatest amount of color possible in that grade’s range.
least amount of color possible in that grade’s range.
De Beers requires its sightholders to have an excellent reputation in the industry and
A. a history of advertising extensively.
B. the ability to cut various types of rough.
C. ownership of a large chain of retail stores.
D. the financial strength to make large purchase commitments.
the financial strength to make large purchase commitments.
In order to exit a diamond, light must strike an inner surface A. at a facet junction. B. inside the critical angle. C. outside the critical angle. D. nearly parallel to the surface.
inside the critical angle.
On a plot, drawing a characteristic only in green indicates that it’s
A. a blemish.
B. part of a mounting.
C. a surface-reaching inclusion.
D. an inclusion totally enclosed within the stone.
a blemish.
Lower half facet length is expressed as a percentage of the A. girdle-to-culet distance. B. table-to-culet distance. C. girdle-to-girdle distance. D. lower half facet-to-culet distance.
girdle-to-culet distance.
De Beers became a privately owned company in A. May 2001. B. June 2003. C. May 2005. D. December 2007.
May 2001.
The term “diamond simulant”
A. includes only manmade stones.
B. means the same as synthetic diamond.
C. refers to a stone with at least one property that’s the same as diamond.
D. refers to a stone that looks like a diamond but has different optical, physical, and chemical properties.
refers to a stone that looks like a diamond but has different optical, physical, and chemical properties.
The diamond industry program designed to ensure that diamonds do not fund civil con- flict or terrorism is called A. integration. B. beneficiation. C. Best Practices. D. the Kimberley Process.
the Kimberley Process.
Diamonds were delivered to the earth’s surface as recently as A. 20 billion years ago. B. 20 million years ago. C. 1 million years ago. D. 10,000 years ago.
20 million years ago.
Scientists succeeded in producing synthetic industrial diamonds for the first time in the A. 1800s. B. 1940s. C. 1950s. D. 1990s.
1950s.
One factor used to determine the clarity grade of a diamond is an inclusion’s A. shape. B. texture. C. contour. D. location.
location.
VS1 and VS2 stones would be expected to have
A. minor included crystals and feathers.
B. inclusions that might threaten durability.
C. minute inclusions and insignificant blemishes.
D. a few scattered pinpoints and light surface graining.
minor included crystals and feathers.
Most diamonds have some symmetry variations
A. that affect the value of the stone.
B. but they rarely affect appearance.
C. that appear both obvious and distracting.
D. but they don’t need to be evaluated when grading.
but they rarely affect appearance.
The basic causes of a diamond’s color are its crystal structure and A. refractive index. B. absorption index. C. strength of saturation. D. chemical composition.
chemical composition.
By 2004, more than 90 percent of manufacturing for the diamond market was done in A. India. B. Israel. C. China. D. South Africa.
India.
Published wholesale diamond price lists are
A. sponsored by De Beers.
B. valid for London and Antwerp only.
C. accurate reports of prices in most wholesale markets.
D. estimates of wholesale prices in a given market at a certain time.
estimates of wholesale prices in a given market at a certain time.
When you color grade a mounted diamond,
A. always remove it from the mounting.
B. you have to use mounted masterstones.
C. tilt the mounting and estimate color through a bezel facet.
D. hold its table beside the masterstone’s table without letting the stones touch.
hold its table beside the masterstone’s table without letting the stones touch.
A scoop is useful for A. sorting diamonds by color. B. sorting diamonds by weight. C. picking up groups of small gems. D. measuring the diameters of small diamonds.
picking up groups of small gems.
A mounting makes it impossible to A. appraise a diamond. B. accurately weigh a diamond. C. estimate a diamond’s proportions. D. locate a diamond’s clarity characteristics.
accurately weigh a diamond.
A group of gems that’s packaged together for sale or storage is called a A. parcel. B. sight box. C. matched set. D. consignment.
parcel.
Inclusions are usually most visible when they’re located A. below the girdle. B. on the girdle plane. C. under the crown facets. D. directly under the table.
directly under the table.
A clarity characteristic confined to the surface of a polished gemstone is called a(n) A. blemish. B. inclusion. C. growth mark. D. surface feature.
blemish.
The most common fancy diamond color is A. pink. B. green. C. brown. D. orange.
brown.
Vast quantities of small, inexpensive diamonds suitable for low-cost, mass-market jewelry are mined in A. India. B. Russia. C. Canada. D. Australia.
Australia.
On an emerald-cut diamond, very narrow corners should be noted under
A. finish, as a polishing detail.
B. finish, as a symmetry variation.
C. proportions, as a shape-appeal factor.
D. proportions, as a length-to-width ratio variation.
proportions, as a shape-appeal factor.
The soft, diamond-bearing material near the surface of a diamond field was named A. blueground. B. easyground. C. yellowground. D. shallowground.
yellowground.
Calculate the estimated weight of a round brilliant with the following dimensions: Average Diameter: 7.25 mm Depth: 5.45 mm Girdle Thickness: Very Thick A. 1.83 cts. B. 1.85 cts. C. 1.88 cts. D. 2.05 cts.
1.83 cts.
The care that goes into the fashioning of a polished diamond, as confirmed by its finish, is its A. cut. B. shape. C. polish. D. craftsmanship.
craftsmanship.
When using the bowing method, star facets that reach one-third of the way toward the girdle make the lines appear A. straight. B. irregular. C. to bow in. D. to bow out.
to bow out.
Grease on the pavilion of a diamond results in
A. more fire.
B. greater brilliance.
C. a smaller critical angle.
D. more light leakage through the pavilion.
more light leakage through the pavilion.
The most commonly observed color of fluorescence in gem diamond is A. blue. B. pink. C. green. D. yellow.
blue.
An included diamond crystal that extends to the surface of a fashioned diamond is called a A. pit. B. chip. C. knot. D. laser drill-hole.
knot.
A diamond imitation that’s foilbacked or composed of colorless lead-glass might be called a A. zircon. B. doublet. C. synthetic. D. rhinestone.
rhinestone.
The origin of a diamond’s color
A. can be determined using a DiamondSure.
B. cannot be determined for most diamonds.
C. should usually be determined by a gemological laboratory.
D. can be easily determined with standard gemological equipment.
should usually be determined by a gemological laboratory.
The most widely accepted lighting for color-grading diamonds is
A. darkfield.
B. ultraviolet.
C. a balance of darkfield and ultraviolet.
D. balanced, daylight-equivalent fluorescent light.
balanced, daylight-equivalent fluorescent light.
A notch scratched into diamond rough to prepare it for cleaving is called a A. tang. B. kerf. C. scaife. D. cleavage.
kerf.
Diamond and graphite are both made of A. carbon. B. helium. C. oxygen. D. nitrogen.
carbon.
Most diamonds from Australia are A. large, but of poor color. B. large and near-colorless. C. small and poor in quality. D. small, but of good quality.
small and poor in quality.
The South African diamond rush was sparked by
A. the arrival of Cecil Rhodes.
B. political changes in Great Britain.
C. reduced supply of Indian diamonds.
D. the discovery of the Star of South Africa.
the discovery of the Star of South Africa.
A profitable mine
A. is close to a source of water.
B. has a high percentage of microdiamonds.
C. meets governmental and environmental regulations.
D. produces diamonds whose value is higher than the mine’s operating costs.
produces diamonds whose value is higher than the mine’s operating costs.
Excessive pavilion bulge on emerald cuts results in A. excess weight. B. increased beauty. C. fewer setting problems. D. unattractive length-to-width ratio.
excess weight.
The rotary saw contributed to the diamond-cutting industry by
A. preventing burned facets.
B. allowing for easier cutting of exotic shapes.
C. allowing for greater weight retention from rough.
D. making it easier to cut through knots and crystals.
allowing for greater weight retention from rough.
A term used to describe any break within a diamond is A. chip. B. bruise. C. feather. D. abrasion.
feather.
African diamonds are recovered from A. pipe deposits only. B. alluvial deposits only. C. marine deposits only. D. pipe, alluvial, and marine deposits.
pipe, alluvial, and marine deposits.
Calculate the total depth percentage of a diamond with the following dimensions: Depth: 4.70 mm Average girdle diameter: 6.54 mm A. 71.0 percent B. 71.9 percent C. 72.0 percent D. 72.1 percent
71.9 percent
Some diamond simulants display “see-through” because, compared to diamond, they A. display less fire. B. have lower hardness. C. can’t be polished as well. D. have much larger critical angles.
have much larger critical angles.
If a diamond has a slight tint in the face-down position and appears colorless in the face- up position, its estimated color grade would be A. D, E, or F. B. G,H,I,orJ. C. K,L,orM. D. N to Z.
G,H,I,orJ.
The size of a finished gem depends greatly upon the rough diamond’s A. color. B. shape. C. country of origin. D. optical properties.
shape.
In the diamond trade, the word “specials” refers to
A. annual diamond sales events.
B. parcels of 5-ct. to 8-ct. rough.
C. diamond rough over 10.80 cts.
D. discounted selections of rough diamonds.
diamond rough over 10.80 cts.
Before the discovery of South Africa’s diamond deposits, the world’s two major producers were India and A. Brazil. B. Russia. C. Australia. D. Venezuela.
Brazil.
A bourse is a(n)
A. agreement to buy on credit.
B. diamond buying and selling club.
C. financial arrangement between miners and cutters.
D. disclosure that a parcel of diamonds has been treated.
diamond buying and selling club.
Crystal shape is an important factor in the evaluation of rough because
A. it influences the clarity grade.
B. it often affects color and clarity.
C. some crystal shapes are much softer than others.
D. it affects the amount of weight retained after cutting
it affects the amount of weight retained after cutting
A diamond’s clarity and color grades indicate its A. quality. B. popularity. C. retail price. D. wholesale price.
quality.
The proportions that play the biggest role in determining a round brilliant diamond’s brightness are table percentage, crown angle, and A. culet size. B. pavilion angle. C. crown height percentage. D. girdle thickness percentage.
pavilion angle.
The concentration of diamonds within a pipe is called A. drift. B. ore grade. C. overburden. D. rough grade.
ore grade.
When using the ratio method for estimating table percentage, a 1:1 1⁄4 ratio indicates a table of approximately A. 54 percent. B. 60 percent. C. 65 percent. D. 69 percent.
60 percent.
In most cases, the easier it is to see a clarity characteristic, the A. less durable the stone. B. lower the clarity grade. C. more durable the stone. D. higher the clarity grade.
lower the clarity grade.
The strongest of all atomic bonds are called A. shells. B. covalent. C. magnetic. D. electrons.
covalent.
Diamonds are more concentrated in A. marine deposits. B. primary deposits. C. volcanic deposits. D. mountain deposits.
marine deposits.
An example of a blemish is a A. chip. B. knot. C. bruise. D. natural.
natural.
The diamond term glassie refers to A. an aggregate mass. B. a well-formed octahedral crystal. C. a noticeably rounded hexoctahedron. D. a macle with an abundance of trigons.
a well-formed octahedral crystal.
To calculate the table percentage of a fancy shape, divide the table size by the stone’s A. width. B. length. C. average diameter. D. diagonal measurement.
width.
The easiest way to separate diamond from zircon is by checking for A. doubling. B. see-through. C. specific gravity. D. refractive index.
doubling.
A gem with triangular and kite-shaped facets that radiate from its center toward its girdle is called a A. step cut. B. mixed cut. C. French cut. D. brilliant cut.
brilliant cut.
What is the correct adjustment factor to use when estimating the weight of an emerald-cut diamond with the following dimensions?
Length: 8.40 mm Width: 5.59 mm Depth: 2.85 mm
A. 0.0080
B. 0.0092
C. 0.0100
D. 0.0106
0.0092
Annealed diamond color can change if it’s exposed to A. ultraviolet rays in sunlight. B. heat during routine repairs. C. chlorine in swimming pools. D. ammonia in cleaning solutions.
heat during routine repairs.
The crystal planes most suitable for cleaving a diamond are the A. cubic planes. B. octahedral planes. C. dodecahedral planes. D. trisoctahedral planes.
octahedral planes.
Atoms in a gem that aren’t part of its essential chemical composition are called A. trace elements. B. foreign elements. C. distortion impurities. D. irregularity elements.
trace elements.
Trade terms that describe diamond color A. can be misleading. B. are accurate for certain stones. C. are usually very clearly defined. D. are based on the names of famous diamantaires.
can be misleading.
Calculate an estimated girdle thickness percentage for the following stone: Total depth percentage: 62.8% Crown height percentage: 15.5% Pavilion depth percentage: 45.5% A. 1.0% B. 1.5% C. 2.0% D. 2.5%
2.0%
The correct conditions for diamond formation exist under A. cratons. B. volcanic ash. C. oceanic crust. D. large mountain ranges.
cratons.
Subduction occurs when A. volcanoes erupt. B. mountains collide. C. tidal waves sweep over landmasses. D. two of the earth’s crustal plates collide.
two of the earth’s crustal plates collide.
The main reason that dealers charge less when diamonds are paid for immediately is that
A. it simplifies their bookkeeping.
B. it reduces the likelihood of returned goods.
C. dealers like to boast of their monthly sales figures.
D. dealers usually borrow money to finance their own purchases.
dealers usually borrow money to finance their own purchases.
A mine’s potential profitability depends in part on A. its ore grade. B. its location on a craton. C. having a small, compact pipe. D. a good kimberlite-to-lamproite ratio.
its ore grade.
The use of synthetic diamonds in jewelry
A. is limited by high production costs.
B. makes up a substantial portion of the market.
C. is limited to fancy-colored melee, which is mostly synthetic.
D. is currently impossible because the synthetics are too highly included.
is limited by high production costs.
Which of the following makes a diamond unsuitable for a masterstone set? A. SI1 clarity B. Yellowish bodycolor C. Very strong fluorescence D. About 43 percent pavilion depth
Very strong fluorescence
An extremely thick girdle
A. makes a stone easier to set.
B. creates an unattractive fish-eye effect.
C. reduces a stone’s durability during normal wear.
D. adds weight without contributing to the stone’s appearance.
adds weight without contributing to the stone’s appearance.
Princess cuts are popular in jewelry designs that call for A. curved lines. B. pavé settings. C. an antique look. D. channel settings.
channel settings.
Large, high-quality diamonds are
A. sorted rather than graded.
B. usually graded in their mountings.
C. graded with a quick look under a loupe.
D. graded much more thoroughly than small, low-quality ones.
graded much more thoroughly than small, low-quality ones.
The crown angle is the angle formed by the girdle plane and the A. table. B. star facets. C. bezel facets. D. upper half facets.
bezel facets.
Diamond’s supreme hardness and durability are
A. due to diamond’s rarity.
B. a result of the conditions under which it formed.
C. surpassed by laboratory-grown diamond substitutes.
D. a result of millions of years of battering by the forces of nature.
a result of the conditions under which it formed.
Which diamond simulant shows noticeable doubling and strong fire? A. CZ B. Zircon C. Synthetic rutile D. Strontium titanate
Synthetic rutile
A surface indentation with tiny, root-like feathers penetrating the stone is called a A. knot. B. cavity. C. bruise. D. natural.
bruise.
To find the crown height percentage, you must know the crown angle and the A. table percentage. B. average girdle diameter. C. pavilion depth percentage. D. girdle thickness percentage.
table percentage.
A loose brown diamond should be color-graded A. using a 10⨉ loupe. B. as a range of colors. C. as a top light brown. D. against a yellow masterstone set.
against a yellow masterstone set.
What is the crown height percentage of a diamond with a crown angle of 32 degrees and a 60 percent table? A. 11.5 percent B. 12.5 percent C. 12.8 percent D. 13.7 percent
12.5 percent
The smallest group of atoms with a characteristic chemical composition and the basic crystal structure of a mineral is called a(n) A. atom. B. unit cell. C. tetrahedron. D. building block.
unit cell.
A city, region, or country with a large number of gemstone manufacturers is called a A. trade center. B. market center. C. cutting center. D. business center.
cutting center.
The involvement of a business or industry in all aspects of its product’s market is called A. best practices. B. blanket marketing. C. electronic retailing. D. vertical integration.
vertical integration.
A knowledgeable, experienced, and successful diamond dealer or manufacturer is called a(n) A. sorter. B. manager. C. auctioneer. D. diamantaire.
diamantaire.
When estimating the weight of very small diamonds, graders
A. often use templates.
B. don’t adjust for proportion variations.
C. use the same techniques as for larger diamonds.
D. must use more adjustment factors than for larger stones.
often use templates.
A “paper-worn” diamond is one that has A. naturals. B. abrasions. C. extra facets. D. a bearded girdle.
abrasions.
A diamond cutter’s main objectives are to produce an attractive finished diamond and A. maximize profits. B. cut round brilliants. C. cut ideal proportions. D. retain as little weight as possible.
maximize profits.
The difference between the RI values of specific violet and red wavelengths of visible light for a given material is its A. fire. B. dispersion. C. critical angle. D. transmission value.
dispersion.
A rapid and efficient way to sort large numbers of small, round diamonds is to use a(n) A. template. B. sieve set. C. electronic scale. D. millimeter gauge.
sieve set.
If a diamond weighs 1.83 cts. and its price is $13,725, what is its per-carat price? A. $750 B. $7,500 C. $13,725 D. $25,116
$7,500
