IGS Professional Gem Reference   

If it’s not listed, you can’t identify it.

 

 

Introduction

 

   Welcome to the IGS Professional Gem Reference. Here you will find gems listed three ways: by name, by refractive index, and by specific gravity.

   The alphabetical listing is provided so you can look up individual gems. We have endeavored to make it as complete as possible. However, to keep the list manageable, we have not included stones that have their species as part of their name. For example, leopard skin jasper would be listed under “jasper” and Burmese ruby under “ruby.”

   The other two lists are for gem identification. Refractive index and specific gravity are shared by fewer gems than any other properties. Knowing these expedites your identification by eliminating the majority of other gems.

 

 

Sample Page

 

IGS Professional Gem Reference    

Alphabetical Listing

 

 

Notes: An * in column “S” (source column,) means the material has been lab created. A blank space means no data available. A dash - means not applicable.

 

 

Material

S

Hard

high

Hard

low

SG

high

SG

low

RI

high

RI

low

Birefringence

O

Disper -

sion

AAPAOK

 

5.5

4.0

2.85

2.60

1.680

1.520

1.35 - 1.55

Agg

 

ACHROITE

 

7.5

7

3.26

3.00

1.655

1.613

.006 - .040

U-

.017

ACTINOLITE

 

5.5

5.5

3.44   

2.95

1.644   

1.614

.022  -  .027

B- A

 

ADAMITE

 

3.5

3.5

4.68

4.32

1.768

1.710

.031  -  .050

B+

 

ADULARIA

 

6.5

6

2.61

2.55

1.536

1.508

.005 - .008

B-

.012

AGATE

 

7

7

2.91

2.55

1.540

1.535

.004

A

.013

AGALMATOLITE

 

2

1

2.90

2.65

1.601

1.534

.050

B -

 

ALABASTER

 

2

2

2.35

2.25

1.53

1.52

.090  -  .010

B+ A

.033

ALBITE

 

6.5

6

2.77

2.57

1.590

1.527

.007 - .010

B+ A

 

ALEXITE

*

8.5

8.25

5.08

4.50

1.900

1.823

-

I

.028

ALLALITE

 

6.5

5.5

3.56

3.17

1.751

1.664

.024  -  .032

B+

 

ALLANITE

 

7

6

4.20

3.38

1.829

1.640

.015  -  .049

B+/-

.019

ALEXANDRITE

*

8.5

8.5

3.8

3.68

1.777

1.740

.008  -  .012

B+/-

.015

ALEXANDRIUM

*

6.5

6.5

4.50

2.30

1.580

1.470

 -

I

 

ALGODONITE

 

4

3

8.38

7.92

 

 

-

I

 

ALLANITE

 

7.5

5.5

4.20

3.38

1.829

1.640

.015  -  .049

B+/-

.019

ALMANDINE GARNET

 

7.5

7

4.30

3.93

1.820

1.760

-

I

.024

AMATITE

*

8.5

8.25

5.08

4.50

1.900

1.823

-

I

.028

AMATRICE

*

5

3.4

2.60

2.20

1.594

1.554

.031

B- A

 

AMAZONITE

 

6.5

6

2.58

2.54

1.534

1.518

.008

B- A

.012

AMBER

 

2.5

2

1.10

1.05

1.545

1.539

 -

A

 -

AMBLYGONITE

 

6

5.5

3.11

2.98

1.633

1.578

.020  -  .027

B+/-

 

AMETHYST

*

7

7

2.69

2.64

1.553

1.544

.009

U+ A

.013

AMETHYSTINE

 

7

7

2.91

2.55

1.540

1.535

.004

A

.013

AMETRINE

 

7

7

2.69

2.64

1.553

1.544

.009

U+ A

.013

AMMOLITE

 

5.5

4.0

2.85

2.60

1.680

1.520

1.35 - 1.55

Agg

 

AMMONITE

 

5.5

4.0

2.85

2.60

1.680

1.520

1.35 - 1.55

Agg

 

ANALCIME

 

5.5

5

2.29

2.22

1.493

1.479

 -

 I

 

ANATASE

 

6

5.5

3.97

3.82

2.564

2.488

.046  -  .067

B

.213 - .259

ANDALUSITE

 

7.5

6.5

3.17

3.13

1.650

1.629

.007  -  .013

B- A

.016

ANDESINE

 

6.5

6

2.77

2.57

1.590

1.527

.007 - .010

B+ A

 

ANDHYDRITE

 

3.5

3

2.98

2.90

1.614

1.570

.044

B+

.013

ANDRADITE GARNET

 

7.5

6.5

4.10

3.70

1.895

1.855

-

I

.057

ANGEL HAIR

*

7

7

2.69

2.64

1.553

1.544

.009

U+ A

.013

ANGEL SKIN

*

4

3.5

2.70

2.43

1.69

1.468

.160  -  .172

A

 

ANGEL STONE

 

4.5

2

2.21

2.1

1.55

1.55

 

 

 

ANGLESITE

 

3

2.5

6.39

6.30

1.894

1.877

.017

B+

.044

ANKERITE

 

4

3.5

3.10

2.85

1.750

1.500

.179  -  .202

U-

 

ANORTHITE

 

6.5

6

2.77

2.57

1.590

1.527

.007 - .010

B+ A

 

ANORTHOCLASE

 

6.5

6

2.77

2.54

1.590

1/514

.005 - .010

B+/- A

 

ANTIGORITE

 

6

2.5

2.80

2.44

1.574

1.490

.001 - .014

B+/- A

 

APACHE TEARS

 

6

5

3

2.33

1.51

1.460

-

I

 

APATITE

*

5

3

3.35

2.5

1.667

1.589

.001  -  .013

U-

.013

APOPHYLLITE

 

5

4.5

2.5

2.3

1.54

1.53

.001 or less

U+/-

 

AQUAMARINE

*

8

7.5

2.9

2.60

1.60

1.560

.004  -  .009

U-

.014

ARAGONITE

 

4

3.5

3

2.47

1.685

1.530

.155

B- A

 

ASPARAGUS STONE

*

5

5

3.35

3.1

1.667

1.589

.001  -  .013

U-

.013

ATTAPULGITE

 

4.5

2

2.21

2.1

1.55

1.55

 

 

 

AUGELITE

 

5

4.5

2.75

2.69

1.59

1.570

.014  -  .020

B+

 

AURORA BOREALIS

*

6

5

4.50

2.30

1.700

1.470

-

I

.009 - .098

AVENTURINE

*

7

7

2.69

2.64

1.553

1.544

.009

U+ A

.013

AXINITE

 

7

6.5

3.36

3.18

1.704

1.656

.010 - .012

B - /+

high

AZURITE

*

4

3.5

3.89

3.30

1.846

1.63

.106  -  .110

B+ A

 

AZURITEMALACHITE

See azurite and malchite