GIA Colored Stones Exam 301-350

Question 1

What characteristic determines iolites value?

Answer 1

predominantly blue face_up color

Question 2

How can iolite be an affordable alternative to tanzanite?

Answer 2

It can sell for about one tenth of the price

Question 3

What is the finest color_change gemstone?

Answer 3

Alexandrite chrysoberyl

Question 4

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

Answer 4

alexandrite

Question 5

What trace element causes alexandrite’s color_change?

Answer 5

chromium

Question 6

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

Answer 6

Alexandrite color change

Question 7

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

Answer 7

Brazil

Question 8

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

Answer 8

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

Question 9

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

Answer 9

it withstands rough wear and is subtly colored

Question 10

The most economically important gem is ___________ .

Answer 10

tanzanite

Question 11

In what area of Tanzania was tanzanite discovered?

Answer 11

Merelani

Question 12

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

Answer 12

Tiffany & Co

Question 13

Tanzanite’s best color is ___________ .

Answer 13

strongly saturated; blue or violetish blue

Question 14

Almost all tanzanite is _______ .

Answer 14

treated

Question 15

Untreated tanzanite is typically what color?

Answer 15

brownish

Question 16

Tanavyte is a trade name for __________ .

Answer 16

purple synthetic YAG

Question 17

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

Answer 17

blue

Question 18

Top color iolite is ____________ .

Answer 18

untreated

Question 19

In what year was alexandrite first discovered?

Answer 19

1830

Question 20

What color characteristic changes during alexandrite’s color_change effect?

Answer 20

hue

Question 21

What color is top_quality alexandrite in daylight?

Answer 21

bluish green

Question 22

The most prized chatoyant gem in the world is __________ .

Answer 22

cat’s_eye chrysoberyl

Question 23

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

Answer 23

Sri Lanka

Question 24

Yellow to yellowish green through grayish green.

Answer 24

Cat’s_eye chrysoberyl

Question 25

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

Answer 25

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

Question 26

What causes cat's_eye chrysoberyl's chatoyancy?

Answer 26

fine needle_like inclusions

Question 27

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

Answer 27

bodycolor; transparency; quality of cutting

Question 28

What does the trade term "milk and honey" mean with cat's_eye chrysoberyl?

Answer 28

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

Question 29

Most gem tourmalines are __________ .

Answer 29

elbaites

Question 30

Most gem tourmalines form in ___________ .

Answer 30

pegmatites

Question 31

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

Answer 31

Brazil

Question 32

The most expensive variety of tourmaline is ________ .

Answer 32

Parabia

Question 33

What trace element causes the color in Parabia?

Answer 33

copper

Question 34

What is the trade term for blue tourmaline?

Answer 34

Indicolite

Question 35

What country is the largest producer of chrome tourmaline?

Answer 35

Tanzania

Question 36

Rubellite tourmaline is colored by what element?

Answer 36

manganese

Question 37

How are many green and blue tourmalines lightened?

Answer 37

heating

Question 38

What treatment is used for many Parabia tourmalines?

Answer 38

heat

Question 39

What trace element causes the color of peridot?

Answer 39

iron

Question 40

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

Answer 40

Arizona

Question 41

Blue zircon is colored by what treatment?

Answer 41

heat treatment

Question 42

Metamict zircons are described as ____________ .

Answer 42

low zircons

Question 43

Which countries produce the finest peridot?

Answer 43

Myanamar and Pakistan

Question 44

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

Answer 44

tourmalines; garnets

Question 45

Why do cutters have to fashion tourmalines in slender proportions?

Answer 45

elongated crystal growth

Question 46

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

Answer 46

tourmalines strong plechroism

Question 47

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

Answer 47

Brazil

Question 48

What are the two most important tourmaline treatments?

Answer 48

heating; irradiation

Question 49

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

Answer 49

Myanmar

Question 50

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

Answer 50

Arizona