GIA Colored Stones Exam 251-300

Question 1

Where is the most important historical ruby source?

Answer 1

Mogok; Myanmar

Question 2

What city and country is the source for the majority of commercial_quality rubies.

Answer 2

Mong Hsu; Myanmar

Question 3

In ancient Sanskrit ruby is called ratnaraj which means ____________ .

Answer 3

king of precious stones

Question 4

The most valuable tone and saturation for ruby are __________ and __________ .

Answer 4

medium to medium dark tone; vivid saturation

Question 5

Corundum can form only in an enviroment that is low in what element?

Answer 5

Silicon

Question 6

Rubies that come from marble deposits are typically low in ___________ .

Answer 6

Iron

Question 7

Ruby that originate in Thailand Cambodia and Madagascar are associated with what type of deposits?

Answer 7

alkali_basalt

Question 8

What is the result from heat treating Mong Hsu rubies?

Answer 8

Eliminates dark centers or cores

Question 9

The worlds largest corundum marketing center is located in what country?

Answer 9

Thailand

Question 10

Switzerland exports rubies that are primarily ________ .

Answer 10

high_end

Question 11

What location has supplied the world with most commercial_quality rubies since 1991?

Answer 11

Mong Hsu

Question 12

The major source for rubies in the 1980’s was what country?

Answer 12

Thailand

Question 13

Compared to rubies from Myanmar; most Thai rubies tend to be ___________ .

Answer 13

darker

Question 14

Rubies from Pailin; Cambodia are similar to those from what country?

Answer 14

Thailand

Question 15

Vietnamese rubies originate in what type of deposit?

Answer 15

marble

Question 16

Where are the Penny Lane and John Saul mines located?

Answer 16

Kenya

Question 17

Newly discovered ruby deposits at Vatomandry and Andilamena are in what country?

Answer 17

Madagascar

Question 18

What three trace elements in differing amounts and combinations cause most fancy sapphire colors?

Answer 18

iron; titanium; chromium

Question 19

What type of fancy sapphire has the highest per_carat value.

Answer 19

padparadschas

Question 20

Other than padparadschas; what color fancy sapphire also commands top prices?

Answer 20

fine pink

Question 21

What colors can be created by heating purple sapphires?

Answer 21

pink or red

Question 22

What location has seen an increase in yellow and orange sapphires?

Answer 22

East Africa

Question 23

An inexpensive natural substitute for diamond is a __________ .

Answer 23

colorless sapphire

Question 24

What is the typical corundum color change?

Answer 24

daylight / blue or violet; incandescent / violetish purple to strongly reddish purple

Question 25

What trace element causes sapphire's color change?

Answer 25

Vanadium

Question 26

The stars in the finest star corundums show these three characteristics ___________; ___________ and __________.

Answer 26

distinct; centered; uniform

Question 27

The finest star corundum has a body color that provides ___________to the __________ .

Answer 27

strong contrast; star

Question 28

What is the most valued star corundum?

Answer 28

star ruby

Question 29

All being equal; which costs LESS; star ruby or blue star sapphire.

Answer 29

blue star sapphires

Question 30

What area is a significant corundum source that promises to be even more productive in the future?

Answer 30

East Africa

Question 31

The name padparadscha means _____________ .

Answer 31

lotus flower

Question 32

What is the trade name for intensely saturated; light to medium pinkish orange to orange_pink sapphires?

Answer 32

padparadscha

Question 33

Color_change sapphire typically changes from blue or violet to ___________ .

Answer 33

reddish purple

Question 34

The most common number of rays in a star corundum is __________ .

Answer 34

six

Question 35

Asterism in black star sapphire is caused by _________ .

Answer 35

hematite

Question 36

The best quality star corundum has what type of tranparency?

Answer 36

semi_transparent

Question 37

Which is the most prized body color in star corundum?

Answer 37

red

Question 38

What trace element causes the pink color of corundum?

Answer 38

chromium

Question 39

Which fancy sapphire hue regularly commands top prices?

Answer 39

pink

Question 40

Green sappire is _______ .

Answer 40

readily available

Question 41

Which color star sapphire is usually cut shallow due to parting?

Answer 41

black

Question 42

What country is the major source of black sapphire?

Answer 42

Australia

Question 43

Fancy sapphires from Montana tend to be __________ .

Answer 43

light in tone

Question 44

The first flame fusion star rubies were produced in what time period?

Answer 44

1940's

Question 45

Strongly saturated blue or violetish blue.

Answer 45

Tanzanite

Question 46

Why must cutters balance tanzanite's weight retention against the quality of face_up color?

Answer 46

Tanzanite's strong plechroism

Question 47

What treatment is used to bring out tanzanite's more attractive blue and violet hues?

Answer 47

heat treatment

Question 48

What country is the only commercial source of tanzanite?

Answer 48

Tanzania

Question 49

What moderately priced commercial_quality stone (when available) is more marketable than commercial_quality tanzanite?

Answer 49

blue sapphire

Question 50

What is the most convincing tanzanite imitation?

Answer 50

synthetic forsterite