GI 12: Detecting Gem Treatments

Question 1

Gem treatments are done for what reason?

Answer 1

Usually done to improve a stone’s appearance

Question 2

What would most likely be found in heat-treated corundum (2)?

Answer 2

1. Discoid Fractures
2. Broken Silk

Question 3

An intense concentration of color around an included crystal that results when the crystal releases titanium during treatment is called what?

Answer 3

Bleeding

Question 4

What might help you find oil or resin fillers in emerald?

Answer 4

Fluorescence

Question 5

What are 2 gems that are routinely irradiated to improve color?

Answer 5

1. Red Tourmaline
2. Blue Topaz

Question 6

Which gem treatment is probably the most widely used today?

Answer 6

Heat Treatment

Question 7

When irradiation is used to enhance a gem’s color it is…

Answer 7

Usually undetectable

Question 8

Typical signs of treatment with lattice diffusion include what?

Answer 8

Color concentrations along facet junctions

Question 9

Separating naturally colored green from treated-colored green diamonds is…

Answer 9

is often impossible.

Question 10

Colorless impregnation is used to do what (2)?

Answer 10

1. Improve appearance
2. Improve stability

Question 11

After a diamond is irradiated, its color might be further altered by..

Answer 11

Annealing

Question 12

Most origin-of-color tests on diamonds should be done by…

Answer 12

by a gemological laboratory

Question 13

Natural jadite that’s untreated is known as what?

Answer 13

Type A

Question 14

Black onyx is actually

Answer 14

dyed black chalcedony

Question 15

Sugar and smoke opal treatments do what?

Answer 15

Darken the stone and bring out its play-of-color

Question 16

Definition:

A treatment that uses chemicals to lighten or remove color

Answer 16

Answer:

Bleaching

Question 17

Definition:
Intense color concentration around a crystal that results when the crystal releases titanium during heat treatment

Answer 17

Answer:

Bleeding

Question 18

Definition:
Diffuse and patchy remains of rutile needles that were partially melted by heat treatment of corundum.

Answer 18

Answer:

Broken Silk

Question 19

Definition:

Filling of pores or other openings with melted wax, resin, polymer, or plastic to improve appearance and stability

Answer 19

Answer:

Colorless Impregnation

Question 20

Definition:

A circular stress fracture that occurs when heat causes and inclusion to expand more than its host gem

Answer 20

Answer:

Discoid Fracture

Question 21

Definition:

A treatment that adds color or affects color by deepening it, making it more even, or changing it

Answer 21

Answer:

Dyeing

Question 22

Definition:

Using a filler to concel fractures and improve the apparent clarity of a gem

Answer 22

Answer:

Fracture (fissure) filling

Question 23

Definition:

A chemical that treaters mix with some resins to cause them to solidify

Answer 23

Answer:

Hardener

Question 24

Definition:

Exposing a gem to rising temperatures for the purpose of changing its appearance

Answer 24

Answer:

Heat treatment

Question 25

Definition: Diamond color modification that uses equipment and conditions similar to those used to grow synthetic diamonds

Answer 25

Answer: High Pressure, High Temperature (HPHT)

Question 26

Definition: Exposing a gem to radiation to change or improve its color

Answer 26

Answer: Irradiation

Question 27

Definition: Using a concentrated beam of laser light to reach a diamond's dark inclusions and disguise or eliminate them

Answer 27

Answer: Laser Drilling

Question 28

Definition: A treatment in which a gem is exposed to high temperatures and chemicals to let color-causing elements penetrate its surface

Answer 28

Answer: Lattice Diffusion

Question 29

Definition: The remains of a mineral inclusion that was altered by heat treatment

Answer 29

Answer: Melt relic

Question 30

Definition: Tinting a cultured pearl with a red dye

Answer 30

Answer: Pinking

Question 31

Definition: Heating a wrapped opal until smoke or ash penetrates its surface to darken it and bring out its play-of-color

Answer 31

Answer: Smoke Treatment

Question 32

Definition: Soaking an opal in a hot sugar solution and then in sulfuric acid to darken it and bring out its play-of-color

Answer 32

Answer: Sugar Treatment

Question 33

Definition: Altering a gem's appearance by applying a backing, coating, or coloring agent like paint

Answer 33

Answer: Surface modification

Question 34

Definition: Any human-controlled process, beyond cutting and polishing, that improves the appearance, durability, or value of a gem

Answer 34

Answer: Treatment

Question 35

Definition: Natural jadeite that's untreated or enhanceds only wth a surface coating of wax

Answer 35

Answer: Type A Jadite

Question 36

Definition: Natural jadeite that's bleached in acid to remove undesireable staining, then impregnated with wax or polymers

Answer 36

Answer: Type B Jadeite

Question 37

Definition: Natural jadeite that's dyed and often bleached and impregnated with wax or polymers

Answer 37

Answer: Type C Jadeite

Question 38

What is one of the oldest gem treatments and probably the most widely used today?

Answer 38

Heat Treatment

Question 39

How can you tell if corundum was heat-treated?

Answer 39

By examining its inclusions under magnification

Question 40

What does HPHT treatment do? (list 2)

Answer 40

1. Eliminate the color of brownish diamonds 2. Create fancy diamond colors

Question 41

T/F: The gem industry requires disclosure of fracture filling?

Answer 41

True

Question 42

Of all the colored stones, what gem is probably the one that's most commonly treated by fracture filling?

Answer 42

Emerald

Question 43

What are some signs of oil or resin fillers? List 4

Answer 43

1. Flash effect 2. Fluorescence 3. Trapped bubbles 4. Seepage of the filler

Question 44

What is the most common diamond treatment?

Answer 44

Fracture filling

Question 45

What are 3 signs of fracture filling in a diamond?

Answer 45

1. flash effect 2. trapped bubbles 3. crackled texture

Question 46

What are 2 signs of glass-filled cavities in corundum?

Answer 46

1. Glassy residue 2. Readily visible bubbles

Question 47

Most orign-of-color tests should be done by...

Answer 47

a gemological laboratory

Question 48

What are 2 effects of modern diamond irradiation?

Answer 48

1. leave little or no color zoning 2. no measurable radioactivity