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Colored Stones Exam > GIA Colored Stones Exam 251-300 > Flashcards

GIA Colored Stones Exam 251-300 Flashcards

1
Q

Where is the most important historical ruby source?

A

Mogok; Myanmar

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2
Q

What city and country is the source for the majority of commercial_quality rubies.

A

Mong Hsu; Myanmar

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3
Q

In ancient Sanskrit ruby is called ratnaraj which means ____________ .

A

king of precious stones

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4
Q

The most valuable tone and saturation for ruby are __________ and __________ .

A

medium to medium dark tone; vivid saturation

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5
Q

Corundum can form only in an enviroment that is low in what element?

A

Silicon

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6
Q

Rubies that come from marble deposits are typically low in ___________ .

A

Iron

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7
Q

Ruby that originate in Thailand Cambodia and Madagascar are associated with what type of deposits?

A

alkali_basalt

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8
Q

What is the result from heat treating Mong Hsu rubies?

A

Eliminates dark centers or cores

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9
Q

The worlds largest corundum marketing center is located in what country?

A

Thailand

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10
Q

Switzerland exports rubies that are primarily ________ .

A

high_end

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11
Q

What location has supplied the world with most commercial_quality rubies since 1991?

A

Mong Hsu

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12
Q

The major source for rubies in the 1980’s was what country?

A

Thailand

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13
Q

Compared to rubies from Myanmar; most Thai rubies tend to be ___________ .

A

darker

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14
Q

Rubies from Pailin; Cambodia are similar to those from what country?

A

Thailand

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15
Q

Vietnamese rubies originate in what type of deposit?

A

marble

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16
Q

Where are the Penny Lane and John Saul mines located?

A

Kenya

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17
Q

Newly discovered ruby deposits at Vatomandry and Andilamena are in what country?

A

Madagascar

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18
Q

What three trace elements in differing amounts and combinations cause most fancy sapphire colors?

A

iron; titanium; chromium

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19
Q

What type of fancy sapphire has the highest per_carat value.

A

padparadschas

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20
Q

Other than padparadschas; what color fancy sapphire also commands top prices?

A

fine pink

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21
Q

What colors can be created by heating purple sapphires?

A

pink or red

22
Q

What location has seen an increase in yellow and orange sapphires?

A

East Africa

23
Q

An inexpensive natural substitute for diamond is a __________ .

A

colorless sapphire

24
Q

What is the typical corundum color change?

A

daylight / blue or violet; incandescent / violetish purple to strongly reddish purple

25
Q

What trace element causes sapphire’s color change?

A

Vanadium

26
Q

The stars in the finest star corundums show these three characteristics ___________; ___________ and __________.

A

distinct; centered; uniform

27
Q

The finest star corundum has a body color that provides ___________to the __________ .

A

strong contrast; star

28
Q

What is the most valued star corundum?

A

star ruby

29
Q

All being equal; which costs LESS; star ruby or blue star sapphire.

A

blue star sapphires

30
Q

What area is a significant corundum source that promises to be even more productive in the future?

A

East Africa

31
Q

The name padparadscha means _____________ .

A

lotus flower

32
Q

What is the trade name for intensely saturated; light to medium pinkish orange to orange_pink sapphires?

A

padparadscha

33
Q

Color_change sapphire typically changes from blue or violet to ___________ .

A

reddish purple

34
Q

The most common number of rays in a star corundum is __________ .

A

six

35
Q

Asterism in black star sapphire is caused by _________ .

A

hematite

36
Q

The best quality star corundum has what type of tranparency?

A

semi_transparent

37
Q

Which is the most prized body color in star corundum?

A

red

38
Q

What trace element causes the pink color of corundum?

A

chromium

39
Q

Which fancy sapphire hue regularly commands top prices?

A

pink

40
Q

Green sappire is _______ .

A

readily available

41
Q

Which color star sapphire is usually cut shallow due to parting?

A

black

42
Q

What country is the major source of black sapphire?

A

Australia

43
Q

Fancy sapphires from Montana tend to be __________ .

A

light in tone

44
Q

The first flame fusion star rubies were produced in what time period?

A

1940’s

45
Q

Strongly saturated blue or violetish blue.

A

Tanzanite

46
Q

Why must cutters balance tanzanite’s weight retention against the quality of face_up color?

A

Tanzanite’s strong plechroism

47
Q

What treatment is used to bring out tanzanite’s more attractive blue and violet hues?

A

heat treatment

48
Q

What country is the only commercial source of tanzanite?

A

Tanzania

49
Q

What moderately priced commercial_quality stone (when available) is more marketable than commercial_quality tanzanite?

A

blue sapphire

50
Q

What is the most convincing tanzanite imitation?

A

synthetic forsterite

Colored Stones Exam (15 decks)

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