| Gemstone |
Hardness |
Method |
Code |
Frequency |
Stability |
Care and Handling |
| Abalone |
|
|
|
|
|
|
| Shell |
3-4 |
none |
N |
n/a |
n/a |
avoid heat / harsh chemicals / perfumes / hairsprays |
| Pearl |
2.5-4 |
none |
N |
n/a |
n/a |
avoid heat / harsh chemicals / perfumes / hairsprays |
Agate - see
Chalcedony |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Alexandrite |
8.5 |
none |
N |
n/a |
n/a |
normal care |
Almandite -
see Garnet |
|
|
|
|
|
|
Amazonite -
see Feldspar |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Amber |
|
|
|
|
|
|
| Amber |
2-2.5 |
none |
N |
r |
n/a |
very soft/avoid harsh chemicals and ultrasonic |
| Amber |
2-2.5 |
heated to improve appearance or deepen color |
E/H |
u |
g-vg |
very soft/avoid harsh chemicals and ultrasonic |
| Amber |
2-2.5 |
dyed or surface treated to add color |
D |
r |
v |
avoid repolishing, harsh chemicals and ultrasonic |
| |
|
|
|
|
|
|
| Amblygonite |
6 |
none |
N |
n/a |
n/a |
*Research in Progress |
Amethyst -
see Quartz |
|
|
|
|
|
|
Ametrine -
see Quartz |
|
|
|
|
|
|
| |
|
|
|
|
|
|
Ammonite/
Ammolite |
4 |
impregnated with colorless hardened substances to increase stability |
I |
u |
f-g |
avoid heat, harsh chemicals and ultrasonic |
| |
|
|
|
|
|
|
| Andalusite |
7-7.5 |
none |
N |
n/a |
n/a |
normal care |
Andradite -
see Garnet |
|
|
|
|
|
|
| Apatite |
|
|
|
|
|
|
| Apatite |
5 |
none |
N |
r |
n/a |
moderately soft, avoid heat, harsh chemicals and ultrasonic |
| Apatite |
5 |
heated to improve appearance or deepen color |
H |
u |
g |
moderately soft, avoid heat, harsh chemicals and ultrasonic |
Aquamarine -
see Beryl |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Aragonite |
3.5-4 |
none |
N |
n/a |
n/a |
soft/avoid heat, harsh chemicals and ultrasonic; generally unsuitable for jewelry |
Aventurine -
see Quartz |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Azurite |
3.5-4 |
coated with colorless wax |
C |
o |
f-g |
soft/avoid heat, harsh chemicals and ultrasonic |
| |
|
|
|
|
|
|
| Azurmalachite |
3.5-4 |
filled with epoxy or resin |
I |
r |
f-g |
soft/avoid heat, harsh chemicals and ultrasonic |
| |
|
|
|
|
|
|
| Benitoite |
6.5 |
none |
N |
n/a |
n/a |
avoid heat, harsh chemicals and ultrasonic |
| |
|
|
|
|
|
|
| Beryl |
|
|
|
|
|
|
| Aquamarine |
7.5-8 |
none |
N |
vr |
n/a |
normal care |
| Aquamarine |
7.5-8 |
heated to improve color |
E/H |
u |
et |
normal care |
| Blue (Maxixe) |
7.5-8 |
irradiated blue from pale pink or colorless |
R |
a |
p |
extra special - avoid light and heat/color fades |
Colorless
(Goshenite) |
7.5-8 |
none |
N |
n/a |
n/a |
normal care |
| Emerald |
7.5-8 |
none |
N |
er |
n/a |
avoid sudden temperature change, ultrasonic and chemicals |
| Emerald |
7.5-8 |
dyed with colored agents |
D |
o |
v |
avoid sudden temperature changes, chemicals and ultrasonic |
| Emerald |
7.5-8 |
penetration of colorless oils, wax and resins into fissures to improve appearance |
E/O |
u |
f-vg |
avoid sudden temperature changes, chemicals and ultrasonic |
| Pink (Morganite) |
7.5-8 |
heated to remove yellow |
E/H |
c |
e |
normal care |
| Red (Bixbite) |
7.5-8 |
none |
N |
r |
n/a |
avoid high temperatures, steam cleaning, chemicals, ultrasonic |
| Red (Bixbite) |
7.5-8 |
colorless oil and resins to improve appearance |
E/O |
c |
f-vg |
avoid high temperatures, steam cleaning, chemicals, ultrasonic |
| Yellow |
7.5-8 |
irradiated to produce color |
R |
u |
v |
normal care, but some stones may fade in light or heat |
| Green - Yellow |
7.5-8 |
none |
N |
n/a |
n/a |
normal care |
Carnelian -
see Chalcedony |
|
|
|
|
|
|
Cat's eye -
see Chrysoberyl |
|
|
|
|
|
|
Bone -
see Ivory |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Chalcedony |
|
|
|
|
|
|
| Agate |
6.5-7 |
dyed |
D |
u |
g-e |
normal care |
| Black Onyx |
6.5-7 |
dyed |
D |
a |
g-e |
normal care |
| Banded Agate |
6.5-7 |
dyed |
D |
u |
e |
normal care |
| Bloodstone |
6.5-7 |
*Research in Progress |
* |
* |
* |
normal care - *Research in Progress |
| Blue Chalcedony |
6.5-7 |
dyed |
D |
c |
f-g |
may fade in light or heat |
| Carnelian |
6.5-7 |
heated to produce color |
E/H |
u |
e |
normal |
| Carnelian |
6.5-7 |
dyed to produce color |
D |
o |
g-e |
certain stones may fade in light or heat |
| Chrysoprase |
6.5-7 |
none |
N |
n/a |
n/a |
normal care |
| Dendritic Agate |
6.5-7 |
none |
N |
n/a |
n/a |
normal care |
| Fire Agate |
6.5-7 |
none |
N |
n/a |
n/a |
normal care |
| Green Chalcedony |
6.5-7 |
dyed to produce color |
D |
u |
f-g |
may fade in light or heat |
| Moss Agate |
6.5-7 |
none |
N |
n/a |
n/a |
normal care |
| Jasper |
6.5-7 |
sometimes dyed to imitate other stones |
D |
o |
e |
normal care |
| Sard |
6.5-7 |
heated to produce color |
E/H |
u |
e |
normal |
| Sard |
6.5-7 |
dyed to produce color |
D |
o |
g-e |
certain stones may fade in light or heat |
| |
|
|
|
|
|
|
| Chrome Diopside |
5-6 |
none |
N |
n/a |
n/a |
moderately soft, avoid sudden temperature changes, harsh chemicals |
Chrome
Tourmaline -
see Tourmaline |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Chrysoberyl |
|
|
|
|
|
|
| Cat's Eye |
8.5 |
none |
N |
n/a |
n/a |
normal |
| Cat's Eye |
8.5 |
irradiated to change color |
R |
o |
e |
normal |
Brown, Yellow,
Green |
8.5 |
none |
N |
n/a |
n/a |
normal |
| |
|
|
|
|
|
|
| Coral |
|
|
|
|
|
|
| Black |
3-4 |
none |
N |
n/a |
n/a |
special - avoid chemicals, cosmetics and ultrasonic |
| White |
3-4 |
bleached |
E/B |
c |
g |
special - avoid chemicals, cosmetics and ultrasonic |
| Pink |
3-4 |
impregnated with colorless wax |
E/W |
c |
g |
special - avoid chemicals and ultrasonic |
| Orange |
3-4 |
stabilized with plastic to improve color and durability |
I |
c |
g |
special - avoid chemicals and ultrasonic |
| Gold |
3-4 |
bleached from black coral |
B |
c |
v-g |
avoid chemicals and ultrasonic |
| Red |
3-4 |
dyed |
D |
u |
v |
special to extra special depending on type of dye - avoid chemicals, cosmetics and ultrasonic |
| |
|
|
|
|
|
|
| Corundum - see Sapphire / Ruby |
|
|
|
o |
|
|
| |
|
|
|
|
|
|
| Danburite |
|
|
|
|
|
|
| White |
7-7.5 |
none |
N |
n/a |
n/a |
normal care |
| Brown |
7-7.5 |
irradiated |
R |
c |
g |
*Research in Progress |
Demantoid -
see Garnet |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Diamond |
|
|
|
|
|
|
| Diamond |
10 |
none |
N |
n/a |
n/a |
normal |
| Diamond |
10 |
laser drilled to improve appearance |
L |
o |
v-g |
normal |
Colorless to
Faint Yellow |
10 |
coated to disguise off color |
C |
r |
p-vg |
color may be affected by polishing, recutting, ultrasonic, alcohol and harsh chemicals |
Colorless to
Faint Yellow |
10 |
fracture filled to improve clarity |
F |
o |
v-g |
avoid extreme heat and recutting |
Colorless to
Faint Yellow |
10 |
heat pressure treated |
HP |
r |
u |
normal |
| Colored |
10 |
use of heat to alter color |
H |
r |
u |
normal |
| Colored |
10 |
laser drilled to improve appearance |
L |
o |
v-g |
normal |
| Colored |
10 |
irradiated and/or heated to produce a variety of colors |
R |
o |
e-vg |
normal |
| Colored |
10 |
fracture filled to improve clarity |
F |
r |
v-g |
avoid extreme heat and recutting |
| Green |
10 |
Irradiated and/or heated to produce green |
R |
o |
e-vg |
special care - avoid heating, color may change |
| |
|
|
|
|
|
|
| Diaspore |
6.5-7 |
none |
N |
n/a |
n/a |
normal |
| |
|
|
|
|
|
|
| Diopside |
5-6 |
none |
N |
n/a |
n/a |
moderately soft, avoid sudden temperature changes, and harsh chemicals |
Dravite - see
Tourmaline |
|
|
|
|
|
|
Emerald -
see Beryl |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Feldspar |
|
|
|
|
|
|
| Amazonite |
6-6.5 |
impregnated with colorless wax, paraffin or oil |
E/W |
u |
f-g |
avoid extreme heat, harsh chemicals and ultrasonic |
| Amazonite |
6-6.5 |
impregnated with hardened resins |
I |
u |
v-g |
avoid chemicals and ultrasonic |
| Labradorite / Spectrolite |
6-6.5 |
none |
N |
n/a |
n/a |
*Research in Progress |
| Moonstone |
6-6.5 |
none |
N |
n/a |
n/a |
normal |
| Orthoclase |
6-6.5 |
none |
N |
n/a |
n/a |
*Research in Progress |
| Plagioclase |
6-6.5 |
none |
N |
n/a |
n/a |
*Research in Progress |
| Sunstone |
6-6.5 |
none |
N |
n/a |
n/a |
*Research in Progress |
Fire Agate -
see Chalcedony |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Fluorite |
|
|
|
|
|
|
Colorless/
Colored |
4 |
none |
N |
n/a |
n/a |
soft, avoid harsh chemicals |
Blue, Green,
Purple |
4 |
irradiated to produce color |
R |
u |
u |
soft, avoid harsh chemicals |
| |
|
|
|
|
|
|
| Garnet |
|
|
|
|
|
|
| Almandite |
7-7.5 |
none |
N |
n/a |
n/a |
normal - avoid sudden temperature change |
| Demantoid |
6.5-7 |
none |
N |
n/a |
n/a |
normal |
| Grossular |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
| Hessonite |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
| Pyrope |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
| Rhodolite |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
Spessartite
(Mandarin) |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
| Topazolite |
6.5-7 |
none |
N |
n/a |
n/a |
normal |
| Tsavorite |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
| Uvarovite |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
Goshenite -
see Beryl |
7.5-8 |
|
|
|
|
|
Green Tourmaline -
see Tourmaline |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Hematite |
5.5-6.5 |
none |
N |
n/a |
n/a |
normal |
Hessonite -
see Garnet |
|
|
|
|
|
|
Hiddenite - see
Spodumene |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Howlite |
|
|
|
|
|
|
| White |
3.3-5 |
none |
N |
na |
n/a |
*Research in Progress |
| Blue |
3-3.5 |
dyed to imitate turquoise |
D |
c |
g |
Very soft, avoid harsh chemicals, ultrasonic, and steaming |
Hyacinth -
see Zircon |
|
|
|
|
|
|
Indicolite - see
Blue Tourmaline |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Iolite |
7-7.5 |
none |
N |
n/a |
n/a |
normal |
| |
|
|
|
|
|
|
| Ivory |
|
|
|
|
|
|
| Ivory / Bone |
2-3 |
bleached to whiten and remove discoloration |
E/B |
c |
g |
very soft, avoid chemicals and ultrasonic, may discolor with time |
| Ivory / Bone |
2-3 |
dyed for artistic purposes |
D |
o |
g |
very soft, avoid chemicals and ultrasonic, may discolor with time |
| Ivory / Bone |
2-3 |
impregnated with colorless paraffin wax |
W |
o |
g |
very soft, avoid chemicals and ultrasonic, may discolor with time |
| Ivory / Mammoth |
2-3 |
impregnated with colorless hardened substances to increase stability |
I |
c |
g |
normal |
| |
|
|
|
|
|
|
| Jade |
|
|
|
|
|
|
| Jadeite |
6.5-7 |
coated with colorless wax |
E/W |
c |
f |
avoid ultrasonic and harsh chemicals |
| Jadeite |
6.5-7 |
bleached and wax impregnated |
B/W |
r |
p |
avoid heat, harsh chemicals and ultrasonic |
Jadeite (Green,
White, Purple) |
6.5-7 |
bleached and polymer impregnated |
B/I |
c |
g-vg |
avoid heat, harsh chemicals and ultrasonic |
Jadeite (Green,
White, Purple) |
6.5-7 |
dyed to imitate natural colors |
D |
o |
v |
avoid strong light, chemicals and ultrasonic |
| Nephrite |
6-6.5 |
dyed |
D |
r |
u |
avoid strong light, harsh chemicals and ultrasonic, may discolor with time |
| |
|
|
|
|
|
|
| Kornerupine |
|
|
|
|
|
|
| Kornerupine |
6.5-7 |
none |
N |
n/a |
n/a |
*Research in Progress |
Cat's Eye
Kornerupine |
6.5-7 |
none |
N |
n/a |
n/a |
*Research in Progress |
| |
|
|
|
|
|
|
| Kyanite |
4-7 |
none |
N |
n/a |
n/a |
very soft in certain directions |
Kunzite - see
Spodumene |
|
|
|
|
|
|
Labradorite -
see Feldspar |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Lapis Lazuli |
|
|
|
|
|
|
| Lapis Lazuli |
5-6 |
coated with wax or oil |
E/W |
c |
f |
avoid chemicals and ultrasonic |
| Lapis Lazuli |
5-6 |
dyed to produce color or uniformity in color |
D |
c |
v |
avoid chemicals and ultrasonic |
| |
|
|
|
|
|
|
| Malachite |
|
|
|
|
|
|
| Malachite |
3.5-4 |
coated with colorless wax |
W |
o |
f |
soft, avoid chemicals and ultrasonic |
| Malachite |
3.5-4 |
impregnated with plastic and/or other hardened agents |
I |
r |
g |
soft, avoid chemicals and ultrasonic |
Mandarin Garnet -
see Spessartite |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Marcasite |
6-6.5 |
none |
N |
n/a |
n/a |
normal |
Maxixe -
see Beryl |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Moldavite |
5.5 |
none |
N |
n/a |
n/a |
normal |
Moonstone -
see Feldspar |
|
|
|
|
|
|
Morganite -
see Beryl |
|
|
|
|
|
|
Moss Agate -
see Chalcedony |
6.5-7 |
|
|
|
|
|
Nephrite -
see Jade |
|
|
|
|
|
|
Oligoclase -
see Feldspar |
|
|
|
|
|
|
Olivine -
see Peridot |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Opal |
|
|
|
|
|
|
White, Black,
Semi-Black |
5.5-6.5 |
natural |
N |
n/a |
n/a |
avoid excessive heat / ultrasonic |
White, Black,
Semi-Black |
5.5-6.5 |
impregnated with colorless oil, wax and resins |
O |
r |
f |
avoid excessive heat, solvents and ultrasonic |
White, Black,
Semi-Black |
5.5-6.5 |
impregnated with colorless plastic to improve durability and color |
I |
r |
g |
avoid excessive heat and solvents |
| Boulder |
5.5-6.5 |
infusion of unhardened colorless substances to improve appearance |
O |
o |
f |
avoid heat, chemicals, ultrasonic and repolishing |
| Cat's Eye Opal |
5.5-6.5 |
impregnated with colorless plastic to improve durability and color |
I |
u |
g |
avoid heat, chemicals, and ultrasonic |
| Fire Opal |
5.5-6.5 |
none |
N |
n/a |
n/a |
avoid heat |
| Hydrophane |
5.5-6.5 |
impregnated with colorless oil, wax and resins |
O |
c |
f |
avoid heat and solvents |
| Hydrophane |
5.5-6.5 |
impregnated with colorless plastic to improve durability and color |
I |
c |
g |
avoid heat and solvents |
| Hydrophane |
5.5-6.5 |
dyed |
D |
c |
g |
avoid heat and solvents |
| Matrix |
5.5-6.5 |
sugar solution infilling in acid bath to darken background |
D |
c |
g |
avoid heat, solvents and repolishing |
Orthoclase -
see Feldspar |
|
|
|
|
|
|
Padparadscha -
see Sapphire |
|
|
|
|
|
|
Paraiba
Tourmaline -
see Tourmaline |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Pearl |
|
|
|
|
|
|
| Natural |
2.5-4.5 |
bleached to improve color and appearance |
B/E |
u |
vg |
special care - avoid cosmetics and household chemicals |
| Natural |
2.5-4.5 |
dyed with or without chemical treatment combined with heat to produce gray to black |
D |
r |
g-vg |
special care - avoid cosmetics and household chemicals and ultrasonic |
| Cultured |
2.5-4.5 |
bleached to improve color and uniformity of white color only |
B/E |
u |
e |
special care - same as above |
| Cultured |
2.5-4.5 |
dyed to give rose, blue or golden overtones |
D |
u |
g |
special care - same as above |
| Cultured |
2.5-4.5 |
dyed blue, black and other colors includes use of colored nuclei |
D |
o |
v |
special care - same as above |
| Cultured |
2.5-4.5 |
dyed all colors (freshwater) |
D |
u |
vg |
special care - same as above |
| Cultured |
2.5-4.5 |
irradiated to produce blue, gray, black and bronze colors |
R |
o |
vg |
special care - same as above |
| Cultured |
2.5-4.5 |
chemical treatment combined with heat to produce gray to black |
D |
c |
g-vg |
special care - same as above |
| Mabe |
2.5-4.5 |
color coated, dyed, bleached, filled with a hardened substance and a MOP back. Sometimes coating can be plastic or polymer to protect the thin nacre |
B/D/I (ASBL) |
a |
f-vg |
extra special care - avoid household chemicals, cosmetics, abrasives, and sudden shocks |
| |
|
|
|
|
|
|
| Peridot |
|
|
|
|
|
|
| Peridot |
6.5-7 |
none |
N |
n/a |
n/a |
normal care |
| Peridot |
6.5-7 |
impregnated with colorless oil, wax and resins |
E/O |
r |
f-g |
avoid sudden temperature changes, harsh chemicals and ultrasonic |
| Peridot |
6.5-7 |
surface fracture filling with a colorless hardened substance |
F |
r |
g |
avoid sudden temperature changes, harsh chemicals and ultrasonic |
| |
|
|
|
|
|
|
| Petalite |
6-6.5 |
*Research in Progress |
* |
* |
* |
*Research in Progress |
| |
|
|
|
|
|
|
| Phenakite |
7.5-8 |
*Research in Progress |
* |
* |
* |
normal care |
| |
|
|
|
|
|
|
| Petrified Wood |
6.5-7 |
none |
N |
n/a |
n/a |
normal care |
| |
|
|
|
|
|
|
| Pietersite |
7 |
none |
N |
n/a |
n/a |
normal care |
Pink Tourmaline -
see Tourmaline |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Pyrite |
6-6.5 |
none |
N |
n/a |
n/a |
avoid harsh chemicals and excessive heat |
Pyrope-see
Garnet |
7-7.5 |
|
|
|
|
|
| |
|
|
|
|
|
|
| Quartz |
|
|
|
|
|
|
| Amethyst |
7 |
none |
N |
n/a |
n/a |
may fade with long exposure to sunlight |
| Amethyst |
7 |
heated to improve color |
H |
r |
e |
avoid exposure to high heat |
| Ametrine |
7 |
none |
N |
n/a |
n/a |
normal care |
| Aventurine |
7 |
none |
N |
n/a |
n/a |
normal care |
| Black |
7 |
irradiated to alter color |
R |
u |
g-e |
normal care |
| Citrine |
7 |
heated to improve color |
E/H |
u |
e |
normal care |
| Ginger |
7 |
irradiated to alter color |
R |
a |
e |
normal care |
| Lilac |
7 |
heated to improve color |
H |
o |
e |
normal care |
| Oro Verde |
7 |
irradiated and heated to produce color |
R |
a |
e |
normal care |
| Smoky |
7 |
irradiated to alter color |
R |
u |
g |
normal care |
| Rock (Colorless) |
7 |
none |
N |
n/a |
n/a |
normal care |
| Rose |
7 |
natural |
N |
n/a |
n/a |
normal care |
| Tourmalinated |
7 |
none |
N |
n/a |
n/a |
normal care |
| Rutilated |
7 |
none |
N |
n/a |
n/a |
normal care |
| Tiger's Eye |
7 |
bleached, dyed or heated |
B/D/H |
o |
g-vg |
avoid harsh chemicals, ultrasonic and steaming |
| Violet |
7 |
heated to improve color |
H |
o |
g-e |
normal care |
| Watermelon |
7 |
heated to improve color |
H |
o |
g-e |
normal care |
| |
|
|
|
|
|
|
| Rhodochrosite |
3.5-4 |
none |
N |
n/a |
n/a |
very soft |
Rhodolite - see
Garnet |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Rhodonite |
5.5-6 |
dyed to make color uniform |
D |
o |
p |
special care - avoid chemicals and ultrasonic |
Rubellite-see
Tourmaline (Red) |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Ruby |
|
|
|
|
|
|
| Ruby |
9 |
natural |
N |
n/a |
n/a |
normal care |
| Ruby |
9 |
heated to improve color and clarity |
E/H |
u |
g-e |
normal care |
| Ruby |
9 |
irradiated to change color |
R |
r |
u |
normal care |
| Ruby |
9 |
intentional filling of surface cavities and fractures |
F/Fh |
c |
f-vg |
avoid caustic acids, extreme pressure, heat and ultrasonic |
| Ruby |
9 |
surface or lattice (bulk) diffusion penetrating most/all of the stone |
U |
o |
g |
special care - avoid repolishing/recutting |
| Ruby |
9 |
dyed with colored oil to improve appearance |
D |
r |
p |
special care - avoid harsh chemicals and ultrasonic |
| Star Ruby |
9 |
surface diffusion of color or asterism |
U |
o |
g |
special care - avoid repolishing/recutting |
| Star Ruby |
9 |
heated to improve color/asterism |
E/H |
c |
g-e |
normal care |
| |
|
|
|
|
|
|
| Sapphire |
|
|
|
|
|
|
| Sapphire |
9 |
natural |
N |
n/a |
n/a |
normal care |
| Sapphire |
9 |
heated to improve color/clarity |
E/H |
u |
e |
normal care |
| Sapphire |
9 |
surface or lattice (bulk) diffusion penetrating most/all of the stone |
U |
o |
g |
special care - avoid repolishing/recutting |
| Sapphire |
9 |
irradiation to produce temporary yellow or orange color |
R |
o |
vp |
extra special - fades quickly in light or heat |
| Star Sapphire |
9 |
surface diffusion of color or asterism |
U |
o |
g |
special care - avoid repolishing/recutting |
| White (Colorless) |
9 |
heated to improve color/clarity |
E/H |
u |
g-e |
normal care |
| Black Star |
9 |
heated |
E/H |
u |
vg |
normal care |
Fancy Colors
(Green, Orange,
Purple, Pink,
Padparadscha,
Yellow) |
9 |
surface or lattice (bulk) diffusion penetrating most/all of the stone |
E/H |
c |
f-g |
special care - avoid repolishing/recutting |
| |
|
|
|
|
|
|
| Scapolite |
|
|
|
|
|
|
| Yellow |
5.5-6 |
none |
N |
n/a |
n/a |
avoid ultrasonic cleaners and exposure to strong sunlight |
| Violet |
5.5-6 |
*Research in Progress |
* |
* |
* |
*Research in Progress |
| |
|
|
|
|
|
|
| Serpentine |
|
|
|
|
|
|
| Serpentine |
2.5-5.5 |
dyed |
D |
c |
f-g |
color may fade |
| Serpentine |
2.5-5.5 |
impregnated with colorless wax |
E/W |
c |
g-vg |
avoid ultrasonic, chemicals and solvents |
| |
|
|
|
|
|
|
| Shell |
4 |
dyed |
D |
c |
f-g |
avoid harsh chemicals |
| |
|
|
|
|
|
|
| Sinhalite |
6.5-7 |
*Research in Progress |
* |
* |
* |
*Research in Progress |
| |
|
|
|
|
|
|
| Sodalite |
5.5-6 |
dyed |
D |
r |
f |
color may fade |
| |
|
|
|
|
|
|
| Sphalerite |
3.5-4 |
none |
N |
n/a |
n/a |
very soft stone, generally not suited for jewelry use |
Spessartite -
see Garnet |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Sphene |
5-5.5 |
none |
N |
n/a |
n/a |
normal care, best used in earrings & pendants due to softness |
| |
|
|
|
|
|
|
Spinel
(all colors) |
8 |
none |
N |
n/a |
n/a |
normal care |
| |
|
|
|
|
|
|
| Spodumene |
|
|
|
|
|
|
| Kunzite |
6.5-7 |
irradiated & heated |
R |
c |
f |
avoid strong light/ultrasonic |
| Kunzite |
6.5-7 |
heated to improve color |
E/H |
c |
f |
color may fade in strong light/sunlight, avoid ulltrasonic |
Hiddenite
(Green) |
6.5-7 |
none |
N |
n/a |
n/a |
color fades in light or heat |
Hiddenite
(Green) |
6.5-7 |
irradiated to produce green color |
R |
r |
p |
extra special care - color fades in light or heat |
| Yellow |
6.5-7 |
irradiated to produce yellow color |
R |
r |
p |
extra special care - color fades in light or heat |
| |
|
|
|
|
|
|
| Sugulite |
6-6.5 |
none |
N |
n/a |
n/a |
normal care |
Sunstone -
see Feldspar |
|
|
|
|
|
|
Tanzanite -
see Zoisite |
|
|
|
|
|
|
Tiger's Eye -
see Quartz |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Topaz |
|
|
|
|
|
|
| Blue |
8 |
irradiated and/or heated to produce blue color |
R |
u |
e |
normal care |
| Brown |
8 |
none |
N |
n/a |
n/a |
may fade with exposure to sunlight |
| Brown |
8 |
irradiated |
R |
o |
p |
will fade |
| Green |
8 |
irradiated to improve the color |
R |
o |
p |
extra special care - color fades in exposure to sunlight |
| Green |
8 |
diffusion of color at or near the surface |
U |
u |
g |
special care - avoid repolishing or recutting |
Mystic, Ocean,
Glacier, Patriot, Canary,
Champagne,
Orchid, Dawn,
Teal, Kiwi
(others) |
8 |
enhanced with various coatings to produce a variety of colors (chemical vapor deposition) |
C |
a |
f |
avoid harsh chemicals, heat, ultrasonic cleaners and repolishing/recutting |
| Pink/Red |
8 |
heated chromium-bearing pinkish-brown to orange stones |
E/H |
u |
e |
normal care |
Yellow /
Orange |
8 |
irradiated to intensify color |
R |
o |
v |
special care - avoid heat and strong light |
| White |
8 |
none |
N |
n/a |
n/a |
normal care |
| |
|
|
|
|
|
|
| Taaffeite |
8-8.5 |
none |
N |
n/a |
n/a |
normal care |
| |
|
|
|
|
|
|
| Tourmaline |
|
|
|
|
|
|
| Cat's Eye |
7-7.5 |
none |
N |
n/a |
n/a |
normal care |
| Chrome |
7-7.5 |
none |
N |
n/a |
n/a |
normal care |
| Green, Blue |
7-7.5 |
none |
N |
n/a |
n/a |
normal care |
| Green, Blue |
7-7.5 |
heated to improve color |
E/H |
c |
e |
normal care |
| Green, Blue |
7-7.5 |
the penetration of colorless oils / unhardened resins |
O |
o |
f-g |
avoid steaming, chemicals, ultrasonic, and temperature changes |
| Paraiba |
7-7.5 |
heated to improve color |
E/H |
c |
g-vg |
normal care |
Pink, Red,
Purple |
7-7.5 |
heated to improve color |
E/H |
o |
e |
normal care |
Pink, Red,
Purple |
7-7.5 |
irradiated to intensify color |
R |
c |
g |
normal care |
Pink, Red,
Purple |
7-7.5 |
penetration of colorless oils or unhardened resins into fissures to improve appearance |
O |
o |
f-g |
special care - avoid temperature changes, steaming, chemicals and ultrasonic |
Pink, Red,
Purple |
7-7.5 |
penetration of coloring agents into voids to improve appearance |
D |
o |
p-f |
special care - avoid temperature changes, steaming, chemicals and ultrasonic |
| Yellow / Orange |
7-7.5 |
heated to improve color |
E/H |
r |
e |
normal care |
| Yellow / Orange |
7-7.5 |
irradiated to improve color |
R |
r |
vg |
normal care |
Tsavorite -
see Garnet |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Turquoise |
|
|
|
|
|
|
| Turquoise |
5-6 |
impregnated with plastic to create or improve color and increase durability |
I |
c |
g |
special care - avoid hot water, household chemicals, and ultrasonic |
| Turquoise |
5-6 |
impregnated with colorless oil or wax to enhance or create color |
W |
c |
p-f |
special care - avoid hot water, household chemicals, and ultrasonic |
| Turquoise |
5-6 |
dyed to improve color |
D |
r |
p |
special care - avoid hot water, harsh household chemicals, and ultrasonic |
| |
|
|
|
|
|
|
| Unakite |
6-7 |
none |
N |
n/a |
n/a |
avoid harsh chemicals |
| |
|
|
|
|
|
|
| Variscite |
4-5 |
none |
N |
n/a |
n/a |
may fade in strong light |
Verdelite - see
Green Tourmaline |
|
|
|
|
|
|
Yellow Beryl -
see Beryl |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| Zircon |
|
|
|
|
|
|
| Blue, Colorless |
6.5-7 |
brownish crystals are heated to improve these colors |
E/H |
a |
p-f |
special care - avoid harsh abrasives and strong light |
| Green / Brown |
6.5-7 |
none |
N |
n/a |
n/a |
special care - avoid harsh abrasives |
| Red |
6.5-7 |
heated to change brownish crystals to red |
E/H |
c |
p-f |
special care - avoid harsh abrasives |
| Yellow |
6.5-7 |
heated to improve color |
E/H |
r |
g-f |
special care - avoid harsh abrasives |
| |
|
|
|
|
|
|
| Zoisite |
|
|
|
|
|
|
| Tanzanite |
6.5-7 |
heated to produce violet/blue color |
E/H |
u |
e |
special care due to hardness |
