Gem Guide

Legends & Lore of Gemstones

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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