Reference Charts & Materials


Commonly used charts and table for jewelers, lapidaries and gemologists.

Diamond Lookalikes Listed by Specific Gravity

Diamond Lookalikes Listed by Specific Gravity

Distinguishing diamond lookalikes from the real thing can be challenging. Learn how to use specific gravity and birefringence to make...
Read More
Standard Gem Sizes Chart

Standard Gem Sizes Chart

Will your gem fit in a standard setting? Use this chart of standard gem sizes for popular cuts and also...
Read More
Gemology Cheat Sheets

Gemology Cheat Sheets

These gemology cheat sheets review gem color and clarity grading, specific information on evaluating diamonds and opals, and basic gem...
Read More
How to Estimate Gem Weight in a Jewelry Setting

How to Estimate Gem Weight in a Jewelry Setting

Although you can't weigh a gemstone in a jewelry setting, you can get a close approximation of the gem weight...
Read More
Table of Gems Ordered by Crystal System

Table of Gems Ordered by Crystal System

This table contains a selection of minerals gemologists may encounter as jewelry stones or gem specimens. The gems are sorted...
Read More
Specific Gravity Values of Selected Gems

Specific Gravity Values of Selected Gems

Measuring specific gravity helps gemologists identify gemstones. The following table lists the specific gravity values for a variety of gem...
Read More
Table of Refractive Indices and Double Refraction of Selected Gems

Table of Refractive Indices and Double Refraction of Selected Gems

Refractive indices and double refraction (birefringence) help gemologists identify gems. The following table lists these values for selected gemstones.
Read More
Properties of Diamond Simulants

Properties of Diamond Simulants

Diamond simulants, like cubic zirconia and moissanite, often appear in jewelry. See how the properties of real diamonds compare with...
Read More
Bead and Necklace Size Charts

Bead and Necklace Size Charts

Whether you’re a novice bead jewelry maker or just shopping for necklaces, these bead and necklace size charts and links...
Read More
The Mohs Hardness Scale and Chart for Select Gems

The Mohs Hardness Scale and Chart for Select Gems

The Mohs hardness scale measures a mineral's resistance to scratching. Find the traditional scale here and a chart of select...
Read More

List of False or Misleading Gemstone Names

A list of False or Misleading Gemstone Names and its Actual Gemological Name. Gathered by the source "Gemstones of the...
Read More
Birthstone Chart

Birthstone Chart

What are the birthstones by month? January is garnet, February is amethyst, March is aquamarine, April is diamond, May is...
Read More

Weights and Measures Conversion Chart

Printable chart to convert weights and measures including Carats, Grams, Kilograms, Ounces, Pounds and Troy Ounces Pounds and Pennyweights.
Read More
Gem Structure Chart

Gem Structure Chart

A gem structure chart that shows various information on a specific structure and gems of example. Details include Refractive Indexes,...
Read More

Ring Size Comparison Chart

Ring Size Comparison Chart compliments of the International Gem Society. A conversion table of Ring sizes. 7 different ring size...
Read More

METAL/WAX FORMULAS

Jewelers need to know how to determine how much gold is needed for a wax mold. Here are three methods...
Read More

Never Stop Learning

When you join the IGS community, you get trusted diamond & gemstone information when you need it.

Become a Member

Get Gemology Insights

Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!