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Colored Stone Essentials > 5 - Treatments, Lab-Grown, Imitations, and Disclosure > Flashcards

5 - Treatments, Lab-Grown, Imitations, and Disclosure Flashcards

1
Q

Treatment

A

Any human-controlled process outside of cutting or polishing that improves the appearance, durability, or value of a gem.

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2
Q

Diamond Bourses

A

Where dealers meet to exchange goods.

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3
Q

Disclosure

A

Clearly and accurately informing customers about the nature of the goods they buy.

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4
Q

What are the ten types of gem treatments?

A

Bleaching
Cavity Filling
Colorless Impregnation
Dyeing
Fracture Filling
Heating
Irradiation
Lattice Diffusion
Sugar & smoke treatments
Surface modification

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5
Q

Bleaching

A

A treatment that uses chemicals to lighten or remove color.

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6
Q

Which two organic gems commonly undergo bleaching, and what bleach is commonly used?

A

Pearls and ivory, with hydrogen peroxide.

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7
Q

What three gems are commonly bleached and what is used?

A

Tiger’s eye, jadeite, chalcedony, with diluted acid and chlorine bleach.

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8
Q

How can bleaching be used to lighten inclusions?

A

Laser-drilling and stronger solvents.

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9
Q

Cavity filling

A

Fills and seals voids to improve appearance and add weight.

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10
Q

What kind of blemishes does cavity filling address?

A

Cavities, pits, and other depressions.

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11
Q

What kind of fillers are typically used in cavity filling?

A

Glass, plastic, and shellac.

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12
Q

In what four gems is cavity filling frequently seen?

A

Tourmaline, opal, ruby, sapphire.

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13
Q

What aspect of durability and what aspect of appearance does cavity filling improve?

A

Durability - hardness; appearance - luster.

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14
Q

Colorless impregnation

A

Filling of pores or other openings with melted wax, resin, polymer, or plastic to improve appearance and stability.

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15
Q

What kind of materials are often used in colorless impregnation?

A

Wax, resin, polymer, and plastic.

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16
Q

What are the benefits of colorless impregnation?

A

Can seal, protect, and improve luster.

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17
Q

What two gems are commonly treated with colorless impregnation?

A

Turquoise, jadeite.

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18
Q

Dyeing

A

Adds or affects color by making it more even or changing it.

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19
Q

What is required before a gem can be dyed?

A

A gem must have a porous surface or fractures that reach the surface.

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20
Q

Quench-crackling

A

When a gem is rapidly heated and cooled to produce surface fractures, in order to prepare for dyeing.

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21
Q

What five gems are typically dyed?

A

Turquoise, cultured pearl, chalcedony, lapis lazuli, jadeite.

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22
Q

How can rock crystal be treated to imitate gems?

A

Rock crystal can be quench-crackled.

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23
Q

Fracture (fissure) filling

A

Using a filler to conceal fractures and improve the apparent clarity of a gem.

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24
Q

What materials are used in fracture filling?

A

Plastic, glass, polymer resins, and oil (Canada balsam and palm oils).

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25
Q

In what gem is fracture filling most common?

A

Emerald

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26
Q

How is ruby typically fracture-filled?

A

Ruby in particular is treated with high-lead-content glass.

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27
Q

Heat treatment

A

Exposing a gem to rising temperatures for the purpose of changing its appearance.

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28
Q

Is heat treatment stable?

A

Yes, under normal wear.

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29
Q

How can heat treatment affect a near-colorless corundum?

A

It gives a blue color.

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30
Q

How can heat treatment affect a dark blue sapphire?

A

It can lighten or eliminate blue.

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31
Q

How can heat treatment affect rubies?

A

It can remove the purplish hue that some rubies have.

32
Q

How can heat treatment affect amber?

A

It can oxidize it and sometimes remove bubbles.

33
Q

Give an example of how heat treatment can add helpful inclusions?

A

It can create asterism.

34
Q

What is the usual length of treatment and chemical used?

A

It varies based on the desired result.

35
Q

What three elements cause a blue color in lattice diffusion?

A

Iron, titanium, beryllium.

36
Q

What two elements cause a red color in lattice diffusion?

A

Chromium, beryllium.

37
Q

What element and process causes blue asterism with lattice diffusion?

A

Titanium dioxide and long cooling.

38
Q

What colors can beryllium induce in lattice diffusion?

A

Pinkish orange, yellow, red, blue.

39
Q

Sugar treatment

A

Soaking an opal in hot sugar solution and then in sulfuric acid to darken it and bring out play-of-color.

40
Q

Smoke treatment

A

Heating a wrapped, usually low-grade opal until smoke or ash penetrates the surface to darken it and bring out play-of-color.

41
Q

What two things do sugar and smoke treatments have in common?

A

They are both surface treatments, and they both work based on carbon entering the stone.

42
Q

Surface modification

A

Altering the appearance by applying backings, coatings, or coloring agents (i.e. paint.)

43
Q

Backing

A

Applied to the pavilion, usually silver/gold foil, fabric, paper, or colored feathers.

44
Q

Where are backings usually used?

A

Costume jewelry

45
Q

What are the five usual types of coatings?

A

Wax, varnish, plastic, ink, and metallic compounds.

46
Q

What type of coating improves the luster of turquoise, jadeite, lapis lazuli, and opal?

A

Wax

47
Q

What are four types of gemstones that sometimes take coatings other than wax?

A

Beryl, corundum, quartz, jadeite.

48
Q

What are the compounds used for coloring agents?

A

Paint, ink, nail polish.

49
Q

What was the initial use of lattice diffusion?

A

Originally used to create asterism in sapphires.

50
Q

What are some popularly treated gems? Try to name 10.

A

Amethyst
Aquamarine
Chalcedony
Citrine
Emerald
Jade
Lapis Lazuli
Opal
Pearl
Ruby
Sapphire
Tanzanite
Tiger’s-eye
Topaz
Turquoise
Zircon

51
Q

What is considered a permanent treatment?

A

Some heat treatments.

52
Q

How difficult is it to detect heat and irradiation?

A

Very.

53
Q

What light feature is a strong indication of treatment?

A

Extraordinary color.

54
Q

Describe irradiation’s vulnerabilities.

A

Can fade quickly in light in any kind, can destabilize with heat.

55
Q

Describe dyeing’s vulnerabilities.

A

Can fade in sun and burn in heat.

56
Q

Describe colorless impregnation’s vulnerabilities.

A

Wax or oil can “sweat” in heat, oils can dry up, standard cleaning can remove treatment.

57
Q

Describe the vulnerabilities of bleaching.

A

Does not hold up against chemicals that stain, can include skin oils.

58
Q

Describe the vulnerabilities of surface treatments.

A

Standard cleaning can remove treatments, heat can vaporize them.

59
Q

What is a common disruptor of treatments?

A

Heat

60
Q

Flame fusion

A

Powdered chemicals are dropped through a high-temperature flame onto a rotation pedestal to produce a synthetic crystal.

61
Q

Who pioneered flame fusion?

A

Verneuil

62
Q

What is the most common and least expensive method of growing synthetic stones?

A

Flame fusion

63
Q

Pulling

A

The synthetic crystal is grown from a seed that is dipped in chemical melt, then pulled away as it gathers material.

64
Q

Flux growth

A

Nutrients dissolve in heated chemicals, then cool to form synthetic crystals.

65
Q

Hydrothermal growth

A

Nutrients dissolve in a water solution at high temperature and pressure, then cool to form synthetic crystals.

66
Q

How do new synthetic gemstone methods affect the market of natural gems?

A

It tends to increase interest in the natural gemstone.

67
Q

Imitation gem

A

Any material that looks like a natural gem and is used in its place.

68
Q

What are natural look-alikes?

A

Other natural gemstones of the same color (i.e. green garnet = emerald)

69
Q

What are lab-grown imitations?

A

Lab-grown gemstones that are not necessarily the same chemical composition and crystal structure (i.e. lab-grown spinel for birthstones)

70
Q

What are plastic imitations?

A

Thoroughly unconvincing plastic replicas.

71
Q

Assembled stones

A

Fusion of 2+ separate pieces of material for a single piece.

72
Q

Doublet

A

Two separate pieces of material fused or cemented together to become a single assembled stone.

73
Q

Triplet

A

A single assembled stone formed from three pieces of material fused or cemented, or from two pieces and a colored cement layer.

74
Q

Phenomenal imitations

A

Manmade processes that can imitate phenomena in non-gems (ex. Cat’s-eye glass)

75
Q

Does the FTC care when you cry?

A

No

76
Q

When should you disclose treatments?

A

Always, along with the 4 Cs.

Colored Stone Essentials (5 decks)

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