GIA Colored Stones Exam 51-100

Question 1

The lapis lazuli trade grade that’s often spotted with green and shows obvious calcite is called ________ .

Answer 1

Chilean

Question 2

The finest color of turquoise is ______________ .

Answer 2

Intense medium blue

Question 3

The purest blue colors of turquoise are caused by _________ .

Answer 3

copper

Question 4

What is the trade term for top_color turquoise?

Answer 4

Persian

Question 5

Turquoise usually forms in __________ .

Answer 5

Limonite

Question 6

What is the color of the markings that sandstone matrix creates in turquoise?

Answer 6

tan

Question 7

Stabalized turquoise is a tade term for what?

Answer 7

Polymer_impregnated turquoise

Question 8

A new turquoise treatment that appeared in the 1980’s and has been used to treat more thabn 10 million carats is _____________ .

Answer 8

Zachary method

Question 9

The major source of turquoise today is ___________ .

Answer 9

Southwestern US.

Question 10

Reconstructed turquoise is __________ .

Answer 10

Immitation

Question 11

Malachite’s color is caused by what element?

Answer 11

Copper

Question 12

The only commercial source of charolite is in what country/

Answer 12

Russia

Question 13

Chalcedony with curved or irregular bands or layers that differ in color and transparency.

Answer 13

Agate

Question 14

A crystal growth habit with a bumpy appearance similar to a bunch of grapes.

Answer 14

Botryodal

Question 15

A cryptocrystalline quartz aggregate.

Answer 15

Chalcedony

Question 16

A property of some crystals that causes them to vibrate at a constant frequency when subjected to an electrical current.

Answer 16

Piezoelectricity

Question 17

A type of sagenitic quartz containing needle_like rutile inclusions.

Answer 17

Rutilated quartz

Question 18

A transparent quartz; usually rock crystal; that contains eye_visable inclusions; often named according to the type of inclusions it contains.

Answer 18

Sagenitic

Question 19

A table_cut gem with a flat or slightly domed top and sometimes a carved design; typically set in men’s rings and cufflinks.

Answer 19

Signet

Question 20

A type of sagenitic quartz containing needle_like or rod_like tourmaline inclusions.

Answer 20

Tourmalated quartz

Question 21

Cryptocrystalline quartz is known as ___________ .

Answer 21

Chalcedony

Question 22

Chalcedony with curved or irregular bands or layers that differ in color and transparency is known as ________ .

Answer 22

Agate

Question 23

What type of crystalline has the smallest crystal size?

Answer 23

Cryptocrystalline

Question 24

In the nineteenth century; a major source of amethyst was discovered in what country?

Answer 24

Brazil

Question 25

The color of amethyst results from __________________ .

Answer 25

Color centers acting on iron .

Question 26

One of amethyst's finest colors is _____________________ .

Answer 26

medium_dark strong reddish purple.

Question 27

What country is the major source for commercial_quality amethyst?

Answer 27

Brazil

Question 28

Maraba amethyst is often

Answer 28

Uniform in color

Question 29

What treatment lightens dark amethyst?

Answer 29

heat

Question 30

How is most of the citrine on the market produced?

Answer 30

By heating amethyst

Question 31

What country is the source for natural ametrine?

Answer 31

Bolivia

Question 32

What type of aggregate is tiger's eye quartz?

Answer 32

microcrystalline

Question 33

Multiple slender crystals or channels cause this in cat's_eye chacelony.

Answer 33

Chatoyancy

Question 34

What is the color of chrysoprase?

Answer 34

Yellowish green

Question 35

Treated black chalcedony is also known by the trade term ____________ .

Answer 35

Black onyx

Question 36

The trade considers what gemstone to have the finest green among the colored stones?

Answer 36

Emerald

Question 37

When all factors are equal; a great difference in emerald value can be caused by slight differences in __________; ____________ and ____________ .

Answer 37

hue; tone and saturation.

Question 38

Emerald's color_causing trace elements are _________ ; __________ and ___________ .

Answer 38

Chromium; Vanadium; Iron

Question 39

What can cause a great reduction in a finished emerald's value?

Answer 39

Poor cutting

Question 40

The trade accepts the fact that most emeralds contain _____________ .

Answer 40

Eye visable inclusions

Question 41

Inclusions that make an emerald less valuable also make it less _____________ .

Answer 41

Transparent.

Question 42

How are emerald's fractures usually filled?

Answer 42

Oil; Resin; Both

Question 43

What type of emerald commands premium prices?

Answer 43

Untreated

Question 44

What is the safest way to clean emeralds?

Answer 44

Gentle scrubbing with warm soapy water.

Question 45

What two countries account for 75% of emerald purchases worldwide?

Answer 45

The US and Japan.

Question 46

What four countries provide most of the world's emeralds?

Answer 46

Brazil; Columbia; Zambia; Zimbabwe

Question 47

The world's emeralds are judged by what country's finest?

Answer 47

Columbia

Question 48

What country's emerald mines have fewer fractures than emeralds from other sources?

Answer 48

Africa

Question 49

What is the most common emerald imitation used in jewelry?

Answer 49

Synthetic spinel triplets

Question 50

What two methods are used to synthesize emeralds?

Answer 50

Flux and hydrothermal