GIA Colored Stones Exam 351-400

Question 1

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

Answer 1

strong double refraction

Question 2

Why does zircon need care in handling and wear?

Answer 2

brittleness

Question 3

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

Answer 3

chrome tourmaline

Question 4

What is the trade term for blue tourmaline?

Answer 4

indicolite

Question 5

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

Answer 5

parti_colored

Question 6

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

Answer 6

rubellite

Question 7

What is the refractive nature of garnet?

Answer 7

single

Question 8

How do gemologists classify garnets?

Answer 8

by their chemistry and their properties.

Question 9

What do dealers base their garnets on?

Answer 9

color or origin

Question 10

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

Answer 10

tsavorite

Question 11

What is the best color for tsavorite?

Answer 11

vivid green; medium to medium_dark tone

Question 12

Tsavorite is colored by what trace element?

Answer 12

vanadium

Question 13

In what area is tsavorite mostly mined?

Answer 13

East Africa

Question 14

Name a transparent green variety of andradite?

Answer 14

demantoid garnet

Question 15

Demantoid garnet is colored by what trace elements?

Answer 15

a mixture of chromium and iron

Question 16

What is the most valuable orange garnet?

Answer 16

spessartite

Question 17

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

Answer 17

hessonite

Question 18

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

Answer 18

pyrope and almandite

Question 19

Dark purplish red to light reddish purple.

Answer 19

Rhodolite’s color range.

Question 20

What is the most valuable red garnet?

Answer 20

rhodolite

Question 21

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

Answer 21

East africa

Question 22

What type of garnet is used in inexpensive mass_market jewelry?

Answer 22

dark_toned; reddish brown calibrated pyrope_almandite

Question 23

Color_change garnets are comprised of a mixture of what species?

Answer 23

pyrope_spessartite

Question 24

What trace element is the coloring agent in color_change garnet?

Answer 24

vanadium

Question 25

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

Answer 25

The higher the chromium content the stronger the red

Question 26

What is the most rare and valuable spinel hue?

Answer 26

red

Question 27

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

Answer 27

spinel

Question 28

Why have many people not seen a natural spinel?

Answer 28

Because natural spinel is rare and synthetic spinel is common

Question 29

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

Answer 29

hollowback

Question 30

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

Answer 30

isomorphous replacement

Question 31

Where is spessartite most commonly found?

Answer 31

pegmatite veins

Question 32

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

Answer 32

D. Grossularite

Question 33

Tsavorite and hessonite are both varieties of __________ .

Answer 33

grossularite

Question 34

All garnets have essentially the same __________ .

Answer 34

crystal structure

Question 35

Rhodolite is a mixture of what varieties of garnet?

Answer 35

almandite and pyrope

Question 36

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

Answer 36

spessartite

Question 37

Dematoid was first discovered in what country?

Answer 37

Russia

Question 38

Tsavorite is colored by what element?

Answer 38

vanadium

Question 39

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

Answer 39

chromium

Question 40

Horsetail inclusions are found in what type of garnet?

Answer 40

dematoid

Question 41

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

Answer 41

East Africa

Question 42

The most valuable spinel color is _________ .

Answer 42

red

Question 43

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

Answer 43

cobalt and iron

Question 44

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 __________ .

Answer 44

brilliance

Question 45

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

Answer 45

brilliant cut

Question 46

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

Answer 46

cabochon

Question 47

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

Answer 47

cameo

Question 48

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

Answer 48

cobbing

Question 49

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

Answer 49

the crown

Question 50

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

Answer 50

Crown/height to pavillion/depth ratio