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Colored Stones Exam > GIA Colored Stones Exam 301-350 > Flashcards

GIA Colored Stones Exam 301-350 Flashcards

1
Q

What characteristic determines iolites value?

A

predominantly blue face_up color

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2
Q

How can iolite be an affordable alternative to tanzanite?

A

It can sell for about one tenth of the price

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3
Q

What is the finest color_change gemstone?

A

Alexandrite chrysoberyl

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4
Q

What color_change gemstone sets the standard against which all other color_change gems are judged?

A

alexandrite

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5
Q

What trace element causes alexandrite’s color_change?

A

chromium

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6
Q

daylight / green to bluish green; incandescent / red to purplish red

A

Alexandrite color change

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7
Q

In what country was a large deposit of alexandrite discovered in the early 1980’s?

A

Brazil

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8
Q

What makes cat’s_eye chrysoberyl the most prized chatoyant gem?

A

excellent hardness; durability; the sharpest cat’s-eye

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9
Q

Why is cat’s_eye chrysoberyl marketed as a man’s gem?

A

it withstands rough wear and is subtly colored

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10
Q

The most economically important gem is ___________ .

A

tanzanite

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11
Q

In what area of Tanzania was tanzanite discovered?

A

Merelani

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12
Q

The name tanzanite was given to transparent blue zoisite by whom?

A

Tiffany & Co

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13
Q

Tanzanite’s best color is ___________ .

A

strongly saturated; blue or violetish blue

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14
Q

Almost all tanzanite is _______ .

A

treated

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15
Q

Untreated tanzanite is typically what color?

A

brownish

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16
Q

Tanavyte is a trade name for __________ .

A

purple synthetic YAG

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17
Q

In iolite; the most valuable main face_up color is ______ .

A

blue

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18
Q

Top color iolite is ____________ .

A

untreated

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19
Q

In what year was alexandrite first discovered?

A

1830

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20
Q

What color characteristic changes during alexandrite’s color_change effect?

A

hue

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21
Q

What color is top_quality alexandrite in daylight?

A

bluish green

22
Q

The most prized chatoyant gem in the world is __________ .

A

cat’s_eye chrysoberyl

23
Q

What country is the major source for cat’s_eye chrysoberyl?

A

Sri Lanka

24
Q

Yellow to yellowish green through grayish green.

A

Cat’s_eye chrysoberyl

25
Q

The color of fine quality cat’s_eye crysoberyl is ____________ .

A

semi transparent golden; yellow to slightly greenish yellow / brownish yellow “honey” color

26
Q

What causes cat’s_eye chrysoberyl’s chatoyancy?

A

fine needle_like inclusions

27
Q

What are the three factors related to the quality of cat’s_eye chrysoberyl?

A

bodycolor; transparency; quality of cutting

28
Q

What does the trade term “milk and honey” mean with cat’s_eye chrysoberyl?

A

one side / original body color; other side / milky appearance.

29
Q

Most gem tourmalines are __________ .

A

elbaites

30
Q

Most gem tourmalines form in ___________ .

A

pegmatites

31
Q

The world’s largest producer of gem_quality tourmaline is ______ .

A

Brazil

32
Q

The most expensive variety of tourmaline is ________ .

A

Parabia

33
Q

What trace element causes the color in Parabia?

A

copper

34
Q

What is the trade term for blue tourmaline?

A

Indicolite

35
Q

What country is the largest producer of chrome tourmaline?

A

Tanzania

36
Q

Rubellite tourmaline is colored by what element?

A

manganese

37
Q

How are many green and blue tourmalines lightened?

A

heating

38
Q

What treatment is used for many Parabia tourmalines?

A

heat

39
Q

What trace element causes the color of peridot?

A

iron

40
Q

Where is the most of the world’s commercial_quality peridot mined?

A

Arizona

41
Q

Blue zircon is colored by what treatment?

A

heat treatment

42
Q

Metamict zircons are described as ____________ .

A

low zircons

43
Q

Which countries produce the finest peridot?

A

Myanamar and Pakistan

44
Q

What two groups of minerals share the same crystal structure but have slightly different chemical and physical properties.

A

tourmalines; garnets

45
Q

Why do cutters have to fashion tourmalines in slender proportions?

A

elongated crystal growth

46
Q

Why must cutters orient finished tourmaline gems carefully to achieve the best colors?

A

tourmalines strong plechroism

47
Q

What country supplies the majority of the world’s gem_quality toumaline?

A

Brazil

48
Q

What are the two most important tourmaline treatments?

A

heating; irradiation

49
Q

What country has the main sources that supply the world with most of its LARGE fine_colored peridot?

A

Myanmar

50
Q

What state in the US supplies the world with rough for much of its commercial_quality calibrated peridot?

A

Arizona

Colored Stones Exam (15 decks)

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