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| Gemstone |
Hardness |
Method |
Code |
Frequency |
Stability |
Care and Handling |
| Abalone |
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| 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 |
|
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| |
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| Alexandrite |
8.5 |
none |
N |
n/a |
n/a |
normal
care |
Almandite -
see Garnet |
|
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Amazonite -
see Feldspar |
|
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| |
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| Amber |
|
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| 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 |
| |
|
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|
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| Amblygonite |
6 |
none |
N |
n/a |
n/a |
*Research
in Progress |
Amethyst -
see Quartz |
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Ametrine -
see Quartz |
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Ammonite/
Ammolite |
4 |
impregnated
with colorless hardened substances to increase stability |
I |
u |
f-g |
avoid
heat, harsh chemicals and ultrasonic |
| |
|
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|
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| Andalusite |
7-7.5 |
none |
N |
n/a |
n/a |
normal
care |
Andradite -
see Garnet |
|
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| Apatite |
|
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| 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 |
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| |
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| Aragonite |
3.5-4 |
none |
N |
n/a |
n/a |
soft/avoid
heat, harsh chemicals and ultrasonic; generally unsuitable for jewelry |
Aventurine -
see Quartz |
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| |
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| Azurite |
3.5-4 |
coated
with colorless wax |
C |
o |
f-g |
soft/avoid
heat, harsh chemicals and ultrasonic |
| |
|
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| Azurmalachite |
3.5-4 |
filled
with epoxy or resin |
I |
r |
f-g |
soft/avoid
heat, harsh chemicals and ultrasonic |
| |
|
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| Benitoite |
6.5 |
none |
N |
n/a |
n/a |
avoid
heat, harsh chemicals and ultrasonic |
| |
|
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| Beryl |
|
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| 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 |
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Cat's eye -
see Chrysoberyl |
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Bone -
see Ivory |
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| Chalcedony |
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| 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 |
| |
|
|
|
|
|
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| Chrome Diopside |
5-6 |
none |
N |
n/a |
n/a |
moderately
soft, avoid sudden temperature changes, harsh chemicals |
Chrome
Tourmaline -
see Tourmaline |
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| |
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| Chrysoberyl |
|
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|
|
|
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| 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 |
| |
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| Coral |
|
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| 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 |
| |
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| Corundum - see Sapphire / Ruby |
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|
o |
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