GIA-DDG 19

Question 1

An industrial process adapted to allow growth of synthetic diamond from carbon-rich gas in thin layers onto a silicon or diamond surface

Answer 1

Chemical Vaport Deposition (CVD)

Question 2

Graphite formation around a diamond’s mineral inclusions and feathers that results from the extreme conditions of HPHT processing

Answer 2

Graphitization

Question 3

The length of time required for half of a group of atoms of a particular type (radioactive) to decay into another type (non-radioactive)

Answer 3

Half-life

Question 4

Diamond synthesis method that mimics the pressure and termperature conditions that lead to natural diamond formation

Answer 4

High pressure, high temperature (HPHT)

Question 5

A clarity treatment that uses a laser to expand an existing cleavage or create a new one, allowing the introduction of a bleaching solution

Answer 5

Internal Laser Drilling (ILD)

Question 6

Exposure of a material to radiation; causes color change in diamonds

Answer 6

Irradiation

Question 7

Using a concentrated bead of laser light to reach a diamond’s dark inclusions and disguise or eliminate them

Answer 7

Laser Drilling

Question 8

A machine used to accelerate electrons to high energy along a straight path

Answer 8

Linear accelerator

Question 9

Manufactured diamond with essentially the same physical, chemical, and optical properties as natural diamond

Answer 9

Synthetic diamond

Question 10

Synthetic diamond is a

Answer 10

manmade diamond with essentially the same physical, chemcal, and optical properties as natural diamond

Question 11

The use of synthetic diamonds in jewelery

Answer 11

is limited by high production costs

Question 12

Most synthetic gem-quality diamonds are

Answer 12

yellow or brown

Question 13

Which one of the following clarity characteristics might be found in a synthetic diamond?

Answer 13

Metallic flux

Question 14

Which one of the following is typical of the UV fluorescence of synthetic diamonds

Answer 14

yellow to greenish yellow under both longwave and shortwave

Question 15

which one of the following is used today to safely color-treat diamonds

Answer 15

high-energy electrons in a linear accelerator

Question 16

GIA laboratory and other gemological laboratories

Answer 16

don’t grade facture-filled diamonds

Question 17

Annealing irradiated diamonds can produce

Answer 17

brown, orange, or yellow

Question 18

Annealed diamond color can change if it’s exposed to

Answer 18

heat during routine repairs

Question 19

The origin of a diamond’s color

Answer 19

should usually be determined by a gemological laboratory

Question 21

Scientists successed in producing synthetic industrial diamonds for the first time in the

Answer 21

1950s

Question 22

Which one of the following is an indication of the HPHT process?

Answer 22

Etched or frosted naturals–also Hourglass graining

Question 23

Laser drill-holes

Answer 23

become permanent clarity characteristics

Question 24

Color treating diamonds in a linear accelerator produces

Answer 24

blue or blue-green colors

Question 25

The flash effect proves that a diamond

Answer 25

is fracture-filled

Question 26

What is the most common diamond treatment?

Answer 26

Fracture Filling

Question 27

T/F-The use of synthetic diaonds in jewelry is limited by high production costs

Answer 27

True

Question 28

What are 3 ways HPHT synthetic diamonds can be identified?

Answer 28

1. Metallic flux inclusions
2. Growth structures (hourglass graining)
3. Fluorescence (yellow to greenish yellow under both longwave and shortwave UV)

Other ways:

1. Phosphorescent
2. Attracted to magnet

Question 29

What are colors of CVD synthetic diamonds?

Answer 29

1. Faint brown to dark brown
2. Near-colorless to colorless
3. Light blue to intense blue

Question 30

What are ways to detect CVD synthetic diamonds?

Answer 30

1. By color
2. Small, irregularly shaped black inclusions (graphite)
3. lack flux metal inclusions common in HPHT synthetics
4. May flouresce a very weak yellow-orange under long wave UV

Question 31

What is DiamondSure and DiamondView?

Answer 31

Developed by De Beers in the mid-1990s. Can separate natural from synthetic colorless or near-colorless diamonds based on the way each absorbs light. Can test both mounted and unmounted gems. Diamonds that don’t pass the DiamondSure’s test can be positively identified by the DiamondView.

Question 32

What are some signs of fracture filling?

Answer 32

• Flash effect
• Trapped Bubbles
• Crackled texture