Gem Guide
Colored Gemstone Guide
Type 1 Gemstone Clarity Chart
VVS Very Very Slightly Included – Minute to not detectable
VS Very Slightly Included – minor
SI1 Slightly Included – NOTICEABLE to obvious
SI2 Slightly Included 2 – OBVIOUS to noticeable
I1 Included 1 – Prominent – moderate effect on appearance or durability
I2 Included 2 – Prominent – severe effect on appearance & durability
I3 Included 3 – Prominent – severe effect on beauty, transparency & durability
Type 1 Gemstones are gemstones that are normally found to be clean. This includes gems such as Amethyst, Aquamarine, Blue Topaz, Citrine, Kunzite, Tanzanite, Yellow Beryl, Chrysoberyl and Diamond.
Type 2 Gemstone Clarity Chart
VVS Very Very Slightly Included – Minor inclusions
VS Very Slightly Included – NOTICEABLE to Obvious
SI1 Slightly Included – Noticeable to OBVIOUS
SI2 Slightly Included 2 – Obvious to Prominent
I1 Included 1 – Prominent – moderate effect on appearance or durability
I2 Included 2 – Prominent – severe effect on appearance & durability
I3 Included 3 – Prominent – severe effect on beauty, transparency & durability
Type 2 Colored Gemstones by their nature have natural inclusions. (Inclusions are the norm) This includes gems such as Andalusite, Chrysoberyl, Alexandrite, Corundum (i.e. Sapphire and Ruby), Garnet, Peridot, Quartz, Amethyst, Citrine, Ametrine, Spinel, Tourmaline and Zircon.
Type 3 Gemstones Clarity Chart
VVS Very Very Slightly Included – NOTICEABLE to obvious
VS Very Slightly Included – Noticeable to OBVIOUS
SI1 Slightly Included – OBVIOUS to prominent
SI2 Slightly Included 2 – Obvious to PROMINENT
I1 Included 1 – Prominent – considerable effect on appearance or durability
I2 Included 2 – Prominent – severe effect on transparency or durability
I3 Included 3 – Prominent – severe effect on beauty, transparency & durability
Type 3 Colored Gemstones by their nature have many natural inclusions. (Heavily Included is the norm) This includes gems such as Emerald, Beryl, Rubellite, and Tourmaline. A rather nice guide for buying gemstones can be found online on the G.I.A. website
Round Brilliant Gemstones Approximate Carat Weight
|
GEMSTONE |
2mm |
3mm |
4mm |
5mm |
6mm |
7mm |
8mm |
|
Alexandrite |
0.04 |
0.12 |
0.35 |
0.63 |
1.3 |
2.15 |
2.9 |
|
Amethyst |
0.04 |
0.1 |
0.2 |
0.4 |
0.7 |
1.3 |
1.8 |
|
Aquamarine |
0.04 |
0.1 |
0.25 |
0.45 |
0.75 |
1.6 |
2.4 |
|
Citrine |
0.04 |
0.1 |
0.2 |
0.4 |
0.7 |
1.3 |
1.8 |
|
Diamond |
0.04 |
0.1 |
0.23 |
0.47 |
0.9 |
1.35 |
1.9 |
|
Emerald |
0.04 |
0.12 |
0.27 |
0.48 |
0.8 |
1.7 |
2.5 |
|
Garnet |
0.05 |
0.13 |
0.3 |
0.6 |
1 |
1.6 |
2.5 |
|
Opal |
0.02 |
0.09 |
0.16 |
0.34 |
0.57 |
0.83 |
1.3 |
|
Peridot |
0.05 |
0.12 |
0.26 |
0.5 |
0.85 |
1.25 |
2 |
|
Ruby |
0.05 |
0.15 |
0.34 |
0.65 |
1.05 |
1.6 |
2.25 |
|
Sapphire |
0.05 |
0.15 |
0.34 |
0.65 |
1.05 |
1.6 |
2.25 |
|
Topaz |
0.04 |
0.11 |
0.3 |
0.56 |
1 |
1.55 |
2.5 |
|
Tourmaline |
0.04 |
0.12 |
0.24 |
0.45 |
0.75 |
1.55 |
2 |
|
Zircon |
0.06 |
0.17 |
0.36 |
0.69 |
1.25 |
1.75 |
2.6 |
Oval Cut Gemstones Approximate Carat Weight
|
GEMSTONE |
5×3 |
6×4 |
7×5 |
8×6 |
9×7 |
10×8 |
11×9 |
12×10 |
14×10 |
16×12 |
18×13 |
|
Alexandrite |
0.3 |
0.61 |
0.8 |
1.45 |
2 |
3.6 |
4.25 |
6 |
8.9 |
12.5 |
18 |
|
Amethyst |
0.23 |
0.45 |
0.85 |
1.25 |
1.75 |
2.4 |
3.2 |
4.5 |
6.5 |
11 |
14 |
|
Aquamarine |
0.2 |
0.4 |
0.75 |
1.1 |
1.75 |
2.25 |
3 |
4.5 |
6.75 |
10.15 |
10.57 |
|
Citrine |
0.23 |
0.45 |
0.85 |
1.25 |
1.75 |
2.4 |
3.25 |
4.2 |
5.2 |
9 |
10.75 |
|
Diamond |
0.25 |
0.5 |
0.75 |
1.4 |
2 |
3 |
4 |
5 |
8 |
11.5 |
16 |
|
Emerald |
0.28 |
0.52 |
0.85 |
1 |
1.6 |
2.25 |
3.75 |
5 |
7.5 |
12 |
14.5 |
|
Garnet |
0.25 |
0.55 |
1 |
1.4 |
2.1 |
2.8 |
3.75 |
5 |
7 |
10 |
13.25 |
|
Opal |
0.16 |
0.28 |
0.47 |
0.75 |
1.1 |
1.65 |
2.15 |
3 |
4 |
5.25 |
5.75 |
|
Peridot |
0.28 |
0.5 |
0.95 |
1.35 |
2 |
2.5 |
3.5 |
4 |
6 |
9.5 |
13 |
|
Ruby |
0.35 |
0.6 |
1 |
1.55 |
2.2 |
3.15 |
3.8 |
6 |
7.25 |
12 |
13 |
|
Sapphire |
0.35 |
0.6 |
1 |
1.55 |
2.2 |
3.15 |
3.8 |
6 |
7.25 |
12 |
13 |
|
Topaz |
0.27 |
0.57 |
1.1 |
1.6 |
2.5 |
3.5 |
4.5 |
6 |
8.8 |
12 |
17 |
|
Tourmaline |
0.25 |
0.5 |
0.9 |
1.18 |
2.3 |
2.9 |
3.5 |
5.25 |
6.8 |
8.5 |
12 |
|
Zircon |
0.4 |
0.75 |
1.45 |
2 |
2.85 |
4 |
5.6 |
7.5 |
8.2 |
13.5 |
14.5 |
Emerald Cut Gemstones Approximate Carat Weight
|
GEMSTONE |
5×3 |
6×4 |
7×5 |
8×6 |
9×7 |
10×8 |
11×9 |
12×10 |
14×10 |
16×12 |
18×13 |
|
Alexandrite |
0.4 |
0.7 |
1.3 |
2.6 |
3.6 |
4.2 |
6 |
8.5 |
9.9 |
14.5 |
22 |
|
Amethyst |
0.35 |
0.55 |
1 |
1.6 |
2.25 |
2.9 |
4.2 |
5.6 |
7.25 |
13 |
17 |
|
Aquamarine |
0.25 |
0.5 |
0.8 |
1.4 |
2 |
3 |
4.3 |
4.75 |
7.75 |
13.5 |
17 |
|
Citrine |
0.35 |
0.55 |
1 |
1.6 |
2.25 |
2.9 |
4.2 |
5.6 |
7.25 |
13 |
17 |
|
Diamond |
0.25 |
0.5 |
1 |
1.5 |
3 |
4 |
5 |
7.8 |
8.8 |
13 |
20 |
|
Emerald |
0.3 |
0.6 |
0.9 |
1.8 |
2.31 |
3.15 |
4.5 |
5.25 |
5.8 |
14 |
17.5 |
|
Garnet |
0.4 |
0.8 |
1.2 |
1.7 |
2.5 |
3.5 |
4.3 |
6.35 |
9 |
17.5 |
21 |
|
Peridot |
0.35 |
0.6 |
1 |
1.7 |
2.25 |
3.8 |
5.25 |
6.25 |
8.8 |
17 |
20 |
|
Ruby |
0.55 |
0.75 |
1.15 |
1.75 |
2.3 |
2.75 |
4 |
6.25 |
9 |
12.5 |
18.7 |
|
Sapphire |
0.55 |
0.75 |
1.15 |
1.75 |
2.3 |
2.75 |
4 |
6.25 |
9 |
12.5 |
18.7 |
|
Topaz |
0.4 |
0.65 |
1.25 |
2.4 |
3.4 |
4 |
5.75 |
8 |
9.5 |
14 |
21 |
|
Tourmaline |
0.3 |
0.6 |
1.6 |
2.15 |
2.8 |
3.6 |
4.3 |
5.2 |
8.5 |
13 |
16.5 |
|
Zircon |
0.6 |
0.8 |
1.7 |
2.35 |
3.9 |
4.5 |
6.2 |
7.05 |
8.95 |
14.3 |
19.9 |
Pear Cut Gemstones Approximate Carat Weight
|
GEMSTONE |
5×3 |
6×4 |
7×5 |
8×5 |
9×6 |
10×7 |
13×8 |
14×10 |
|
Alexandrite |
0.3 |
0.5 |
0.85 |
1.1 |
2.1 |
3.6 |
6.6 |
8.8 |
|
Amethyst |
0.2 |
0.35 |
0.65 |
0.85 |
1.25 |
1.7 |
4 |
5 |
|
Aquamarine |
0.2 |
0.35 |
0.65 |
0.9 |
1.3 |
1.85 |
4.2 |
5.6 |
|
Citrine |
0.2 |
0.35 |
0.65 |
0.85 |
1.3 |
1.7 |
4 |
5 |
|
Diamond |
0.25 |
0.5 |
0.75 |
1 |
1.5 |
2 |
3.5 |
5 |
|
Emerald |
0.25 |
0.45 |
0.7 |
1.05 |
1.7 |
2.6 |
4.15 |
6.1 |
|
Garnet |
0.25 |
0.4 |
1 |
1.15 |
1.3 |
1.8 |
3.5 |
5.8 |
|
Opal |
0.13 |
0.22 |
0.35 |
0.5 |
0.7 |
1.03 |
1.4 |
2.45 |
|
Peridot |
0.25 |
0.45 |
0.7 |
0.8 |
1.1 |
1.4 |
3.4 |
4.75 |
|
Ruby |
0.3 |
0.5 |
0.75 |
1 |
1.85 |
2.5 |
4.75 |
7.9 |
|
Sapphire |
0.3 |
0.5 |
0.75 |
1 |
1.85 |
2.5 |
4.75 |
7.9 |
|
Topaz |
0.25 |
0.5 |
1 |
1.1 |
2 |
3.5 |
6.5 |
8.5 |
|
Tourmaline |
0.35 |
0.45 |
0.6 |
0.9 |
1.1 |
1.4 |
2.8 |
6.75 |
|
Zircon |
0.3 |
0.7 |
1 |
1.3 |
2.6 |
4 |
5.25 |
7.5 |
Marquise Cut Gemstones Approximate Carat Weight
|
GEMSTONE |
4×2 |
6×3 |
8×4 |
10×5 |
12×6 |
14×7 |
|
Alexandrite |
0.07 |
0.3 |
0.7 |
1.25 |
2.1 |
3.5 |
|
Amethyst |
0.1 |
0.2 |
0.48 |
0.9 |
1.59 |
2.45 |
|
Aquamarine |
0.08 |
0.2 |
0.5 |
0.8 |
1.5 |
2.75 |
|
Citrine |
0.1 |
0.2 |
0.5 |
0.9 |
1.59 |
2.45 |
|
Diamond |
0.12 |
0.25 |
0.5 |
1 |
2 |
3 |
|
Emerald |
0.09 |
0.3 |
0.6 |
1.1 |
1.8 |
2.8 |
|
Garnet |
0.09 |
0.25 |
0.6 |
1.2 |
2 |
2.85 |
|
Opal |
0.09 |
0.17 |
0.37 |
0.59 |
1 |
1.25 |
|
Peridot |
0.1 |
0.25 |
0.5 |
1 |
2 |
2.55 |
|
Ruby |
0.13 |
0.35 |
0.75 |
1.15 |
2.2 |
3 |
|
Sapphire |
0.13 |
0.35 |
0.75 |
1.15 |
2.2 |
3 |
|
Topaz |
0.07 |
0.3 |
0.7 |
1.2 |
2 |
3.4 |
|
Tourmaline |
0.1 |
0.3 |
0.6 |
0.85 |
1.55 |
2.2 |
Gemstone Enhancements
|
Gemstone |
Code |
Enhancement Method |
Use |
Stability |
Care |
|
Alexandrite |
N |
None |
N/A |
N/A |
Normal |
|
Amethyst |
H |
Heated to Lighten Color |
Occasional |
Excellent |
Special |
|
Aquamarine |
H |
Heated to remove yellow |
Usually |
Excellent |
Normal |
|
Beryl-Red |
H or O |
Colorless Oil to fill fissures |
Common |
Very Good |
Special |
|
Beryl-Pink |
H |
Heated to remove yellow |
Common |
Excellent |
Normal |
|
Chrysoberyl |
N |
None |
N/A |
Excellent |
Normal |
|
Chrysoberyl-Cats Eye |
R |
Irradiated to Change Color |
Occasional |
Excellent |
Normal |
|
Diamond-Colorless |
LC |
Laser drilled to improve appearance |
Common/Occasional |
Very Good |
Normal |
|
Diamond-Colored |
LC,F, or R |
Laser drilled to improve appearance |
Very Good |
Very Good |
Normal |
|
Irradiated for fancy color |
|||||
|
Occasional |
Fair/Poor |
Special |
|||
|
Emerald |
H or O |
Oil, Wax or Resin to improve appearance |
Common |
Fair/Very Good |
Special |
|
Garnet |
N |
None |
N/A |
N/A |
Normal |
|
Kunzite |
H |
Heated to improve color |
Common |
Fair |
Special |
|
Opal-White,Black |
N |
None |
N/A |
N/A |
Special |
|
Opal-White,Black |
O |
Impregnated with Oil |
Rarely |
Fair |
Special |
|
Opal-Boulder |
N |
None |
N/A |
N/A |
Normal |
|
Opal-Boulder |
O |
Infusion of colorless substances |
Occasional |
Fair |
Special |
|
Opal-Fire |
N |
None |
N/A |
N/A |
Special |
|
Pearl-Natural |
B |
Bleached to improve color |
Common |
Very Good |
Special |
|
Pearl-Natural |
D |
Dyed to produce grey/black |
Rarely |
Good/Very Good |
Special |
|
Peridot |
N |
None |
N/A |
N/A |
Normal |
|
Peridot |
H or O |
Improve appearance |
Rarely |
Good/Fair |
Special |
|
Ruby |
N |
None |
N/A |
N/A |
Normal |
|
Ruby |
H |
Improve color/appearance |
Usually |
Excellent |
Normal |
|
Ruby |
D or F |
Improve color/appearance |
Common |
Good/Poor |
Special |
|
Ruby |
DI |
Artificial color |
Occasional |
Good |
Special |
|
Sapphire |
N |
None |
N/A |
N/A |
Normal |
|
Sapphire |
H |
Improve color/appearance |
Usually |
Excellent |
Normal |
|
Sapphire |
DI |
Artificial color |
Common |
Good |
Special |
|
Sapphire |
R |
Intense yellow or orange color |
Occasional |
Very Poor |
Special |
|
Spinel |
N |
None |
N/A |
N/A |
Normal |
|
Tanzanite |
H |
Heated to produce blue/violet color |
Usually |
Excellent |
Special |
|
Topaz-Blue |
R/H |
Heated/Irradiated for color |
Usually |
Excellent |
Normal |
|
Topaz-Yellow/Orange |
R |
Intensify color |
Occasional |
Fair |
Special |
|
Topaz-Pink |
H |
Heated for color |
Usually |
Excellent |
Normal |
|
Topaz-Green |
R |
Irradiated to produce color |
Usually |
Good |
Special |
|
Tourmaline |
N |
None |
N/A |
N/A |
Normal |
|
Tourmaline |
H |
Heated for color |
Common |
Excellent |
Normal |
|
Tourmaline |
R |
Irradiated to intensify color |
Common |
Good |
Normal |
|
Zircon |
N |
None |
N/A |
N/A |
Special |
|
Zircon |
H |
Heated for color |
Rarely |
Good |
Special |
B Bleaching-Artificial Color
D Dyeing-Artificial Color
F Filling-Durability/Appearance
H Heating-Color/Clarity
R Irradiation-Color Enhancement
O Oiling/Resin Infusion-Appearance
N None
DI Diffusion-Chemicals and High Temperature-Artificial Color
WO Waxing Oiling-Colorless Wax or Oil Introduced for Clarity
LC Laser/Chemicals-Laser Chemicals to alter inclusions
PI Plastic Introduction-Durability/Appearance
WO Waxing Oiling-Appearance
HP Heating/Pressure-Color/Clarity
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