Properties of Diamond Simulants
Gem-grade synthetic diamonds rarely appear in jewelry. However, diamond simulants often do. Identifying these look-alike materials is an important skill for gemologists.
Diamond Look-alike Comparison Chart
Distinguishing a diamond look-alike from the real thing can challenge new gemologists. However, specific gravity and birefringence hold the key to simple separations.
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 by determining its volume.
Gem Structure Chart
Structure Crystal axes and Angles Optic Character Refractive Indexes Optic Sign Pleochroism Examples Amorphous No orderNo axes IsotropicSingly refractive 1 RI None None Opal, Amber, Glass, Plastic Isometric 1 axis…
List of False or Misleading Gemstone Names
False Gemstone Name Actual Gemological Name Adelaide ruby Almandite African emerald Green fluorite Alaska diamond Rock crystal (quartz) American jade Green idocrase American ruby Pyrope or almandite (garnet)…
Jewelers need to know how to determine how much gold is needed for a wax mold. Here are three methods for you: METAL METAL/WAX RATIO SILVER 10.5 – 1 GOLD 10K 13 – 1 GOLD 14K 14- 1 GOLD 18K 16 – 1 PLATINUM 22 -…
Select Gems Ordered By Density
Gemstone Density Gold 15.5 -19.3 Thorianite 9.7 – 9.8 Silver 9.6 – 12.0 Algondonite 8.38 Bismutotantalite 8.15 – 8.89 Cinnabar 8.0 – 8.2 Stolzite 7.9 -…
The Mohs Hardness Scale And Chart For Select Gems
The Mohs Hardness Scale 10 Diamond 9 Corundum 8 Topaz 7 Quartz 6 Feldspar 5 Apatite 4 Fluorite 3 Calcite 2 Gypsum 1 Talc Select Gems Ordered By Mohs…
Standard Gem Sizes Chart
Purpose: Mass produced gem settings come in standard sizes. If a gem won’t fit in a standard setting, a setting should be custom made. This involves much more labor and therefore expense. Bear this in mind when purchasing a gem, or selecting a cut…
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 by their crystal system.
Table of Refractive Index and Double Refraction of Gems
Gemstone Refractive Index Double Refraction Hematite 2.940 – 3.220 0.287 Cinnabar 2.905 – 3.256 0.351 Proustite 2.881 – 3.084 0.203 Pyrargyrite 2.88 – 3.08 0.200 Cuprite 2.849 none Rutile 2.616 -…
Weights and Measures Conversion Chart
1″ = 25.4 mm 1 mm =…
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