GIA Colored Stones Exam 501-550

Question 1

A synthetic crystal growth method in which the chemical mixture is melted; then recrystalized.

Answer 1

melt process

Question 2

A synthetic crystal growth method that uses cooling pipes around an interior of melted chemical ingredients.

Answer 2

skull melt

Question 3

A growth method in which the synthetic crystal grows from a dissolved chemical mixture; sometimes at high temperatures an pressure.

Answer 3

solution process

Question 4

A synthetic growth method that starts WITHOUT a seed crystal.

Answer 4

spontaneous nucleation

Question 5

Most synthetic gems are produced by either what two processes?

Answer 5

melt; solution

Question 6

A mass of tiny; randomly oriented crystals.

Answer 6

aggregate

Question 7

A smooth; flat break in a gemstone parallel to planes of atomic weakness; caused by weak or few bonds between atoms; or both.

Answer 7

cleavage

Question 8

A curved and ridged fracture in a gemsotne; extending from the surface inward.

Answer 8

conchoidal fracture

Question 9

An aggregate made up of individual crystals detectable only under very high magnification.

Answer 9

cryptocrystalline

Question 10

How heavy an object is in relation to its size.

Answer 10

density

Question 11

A gemstones ability to withstand wear; heat and chemicals.

Answer 11

durability

Question 12

Any break in a gem other than cleavage or parting.

Answer 12

fracture

Question 13

The characteristic external crystal shape or form of a mineral.

Answer 13

habit

Question 14

How well a gemstone resists scratches. Usually expressed in terms of the Mohs scale; with diamond the harderst (10) and talc the softest (1).

Answer 14

hardness

Question 15

An aggregate made up of individual crystals visable under magnification.

Answer 15

microcrystalline

Question 16

A flat break in a gemstone caused by concentrated included minerals parallel to a twinning plane.

Answer 16

parting

Question 17

How well a gemstone resists light; heat; and chemicals is called ___________ .

Answer 17

stability

Question 18

Ratio of the weight of a matrial to the weight of an equal volume of water.

Answer 18

specific gravity

Question 19

Damage caused by sudden; extreme temperature changes.

Answer 19

thermal shock

Question 20

A hollow cavity in a gem; filled with a liquid; a gas; and one or more crystals.

Answer 20

Three_phase inclusion

Question 21

Atoms of a gem that aren’t part of its essential chemical composition.

Answer 21

trace element

Question 22

Change in a gem’s crystal direction during or after growth.

Answer 22

twinning

Question 23

Location of a change in crystal growth direction.

Answer 23

twinning plane

Question 24

A hollow cavity in a gem; usually filled with a liquid AND a gas.

Answer 24

Two_phase inclusion

Question 25

The smallest group of atoms with both the characteristic chemical composition and crystal structure of a mineral.

Answer 25

unit cell

Question 26

A unit cell defines a mineral's ___________ .

Answer 26

basic identity

Question 27

If a crystal grows in a flux that is highly saturated with the necessary elements it tends to be ___________ .

Answer 27

small

Question 28

What aggregate's crystals are visible only with magnification greater than a standard gemological microscope?

Answer 28

cryptocrystalline

Question 29

Which is classified in the orthorhobic system? A. Beryl B. Topaz C. Garnet D. Corundum

Answer 29

B. Topaz

Question 30

Which element causes the red in ruby and the green in emerald?

Answer 30

chromium

Question 31

What type of twinning is caused by enviromental change after the gem forms?

Answer 31

polysynthetic

Question 32

What type of twinning looks as if two crystal halves are mirror images?

Answer 32

contact

Question 33

Needles of actinolite found in emerald are classified as what?

Answer 33

inclusions

Question 34

A two_phase inclusion is a cavity in a gem that's typically filled with a ___________ and a __________ .

Answer 34

liquid and gas

Question 35

Atoms in a gem that are not part of its essential chemical composition are called what?

Answer 35

trace elements

Question 36

The trace elements that cause corundum's blue are ____________ and ________ .

Answer 36

iron and titanium

Question 37

An object's weight in relation to its size is called its ____________ .

Answer 37

density

Question 38

Which gems are cryptocrystalline? A. opal and amethyst B. nephrite and jadeite C. chalcedony and turquoise

Answer 38

C. chalcedony and turquoise

Question 39

Rough spinel often occurs as what type of crystals?

Answer 39

twinned

Question 40

Many fashioned rubies have shallow proportions because they're cut from what type of crystals?

Answer 40

flat

Question 41

What are the three different ways a gem can break?

Answer 41

cleavage and parting and fracture

Question 42

A gem's price divided by its carat weight is called ___________ .

Answer 42

per_carat price

Question 43

The international unit of measurement for gem weight is the _________ .

Answer 43

metric carat

Question 44

Individual stone prices are referred to as __________ .

Answer 44

unit prices

Question 45

How many points are in a metric carat?

Answer 45

100

Question 46

A metric carat equals __________ gram(s).

Answer 46

0.20 gram

Question 47

How are most colored stones sold?

Answer 47

by weight

Question 48

What category of colored stone is often sold per piece?

Answer 48

small; inexpensive

Question 49

Sieves are most useful for sorting round gems with diameters that are what size?

Answer 49

3mm and below

Question 50

When you first start to count a large pile of small gems; it's best to seperate them into groups of how many?

Answer 50

5