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Colored Stones Exam > GIA Colored Stones Exam 351-400 > Flashcards

GIA Colored Stones Exam 351-400 Flashcards

1
Q

What easily distinguishes colorless zircon from diamond or synthetic cubic zirconia?

A

strong double refraction

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2
Q

Why does zircon need care in handling and wear?

A

brittleness

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3
Q

What is the trade term for a vibrant green tourmaline that is colored by traces of vanadium; chromium or both?

A

chrome tourmaline

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4
Q

What is the trade term for blue tourmaline?

A

indicolite

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5
Q

Gems that show color zoning with two or more colors is known as ___________ .

A

parti_colored

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6
Q

What is the trade name for a pink to red elbaite tourmaline?

A

rubellite

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7
Q

What is the refractive nature of garnet?

A

single

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8
Q

How do gemologists classify garnets?

A

by their chemistry and their properties.

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9
Q

What do dealers base their garnets on?

A

color or origin

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10
Q

What type of garnet has properties that make it an effective and less expensive alternative to emerald?

A

tsavorite

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11
Q

What is the best color for tsavorite?

A

vivid green; medium to medium_dark tone

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12
Q

Tsavorite is colored by what trace element?

A

vanadium

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13
Q

In what area is tsavorite mostly mined?

A

East Africa

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14
Q

Name a transparent green variety of andradite?

A

demantoid garnet

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15
Q

Demantoid garnet is colored by what trace elements?

A

a mixture of chromium and iron

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16
Q

What is the most valuable orange garnet?

A

spessartite

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17
Q

Name a transparent orange to cinnamon_colored variety of the grossularite species of garnet?

A

hessonite

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18
Q

Rhodolite and most red garnets are a mixture of what two garnet species?

A

pyrope and almandite

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19
Q

Dark purplish red to light reddish purple.

A

Rhodolite’s color range.

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20
Q

What is the most valuable red garnet?

A

rhodolite

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21
Q

What area has been the most important source of rhodolite since the 1960’s?

A

East africa

22
Q

What type of garnet is used in inexpensive mass_market jewelry?

A

dark_toned; reddish brown calibrated pyrope_almandite

23
Q

Color_change garnets are comprised of a mixture of what species?

A

pyrope_spessartite

24
Q

What trace element is the coloring agent in color_change garnet?

A

vanadium

25
Q

In spinel; what trace element causes the strength of red in garnet?

A

The higher the chromium content the stronger the red

26
Q

What is the most rare and valuable spinel hue?

A

red

27
Q

What gemstone forms in the same metamorphic rock as corundum and is found in the same alluvial deposits?

A

spinel

28
Q

Why have many people not seen a natural spinel?

A

Because natural spinel is rare and synthetic spinel is common

29
Q

A cabochon with a curved; undercut bottom; designed to lighten the tone of the gem material is called a ___________ .

A

hollowback

30
Q

The substitution of one chemical element for another in the crystal structure of a mineral is called _________ .

A

isomorphous replacement

31
Q

Where is spessartite most commonly found?

A

pegmatite veins

32
Q

Which of the following has the widest color range? A. Rhodolite B. Almandite C. Spessartite D. Grossularite

A

D. Grossularite

33
Q

Tsavorite and hessonite are both varieties of __________ .

A

grossularite

34
Q

All garnets have essentially the same __________ .

A

crystal structure

35
Q

Rhodolite is a mixture of what varieties of garnet?

A

almandite and pyrope

36
Q

Mandarin garnet has been used as a trade name for __________ .

A

spessartite

37
Q

Dematoid was first discovered in what country?

A

Russia

38
Q

Tsavorite is colored by what element?

A

vanadium

39
Q

The intense red color of spinel is caused by what element?

A

chromium

40
Q

Horsetail inclusions are found in what type of garnet?

A

dematoid

41
Q

The most important source of rhodolite in recent years has been in what area?

A

East Africa

42
Q

The most valuable spinel color is _________ .

A

red

43
Q

The most desirable; vibrant; and rare blue natural spinels are colored by what elements?

A

cobalt and iron

44
Q

Light that eventually returns to the eye after entering a gem through the crown; reflecting off its pavilion facets; and exiting back through the crown is known as __________ .

A

brilliance

45
Q

A cutting style with triangular or kite_shaped facets that radiate from the center toward the girdle is called a __________ .

A

brilliant cut

46
Q

A smoothly rounded polished gem with a domed top and a flat or curved base is called a _________ .

A

cabochon

47
Q

A gem carving style in which the design; often a women’s profile; projects slightly from a flat or curved surface is called a ________ .

A

cameo

48
Q

Removing heavily included sections from gemstone rough by carefully tapping it with a small hammer is called ___________ .

A

cobbing

49
Q

The top part of the gem above the girdle is called __________ .

A

the crown

50
Q

The relationship of the height of a gem’s crown to the depth of tis pavilion; judged by viewing its profile is called _____________ .

A

Crown/height to pavillion/depth ratio

Colored Stones Exam (15 decks)

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