Polariscope Guide, Part 1: Testing Gemstone Refraction
The polariscope is one of gemology’s simplest and most useful tools. With a little practice and our three-part polariscope guide, you’ll…
Polariscope Guide, Part 3: Testing For Gemstone Twinning, Dichroism, and Crystal Strain
A gemologist can conduct many different tests with a polariscope. Gemstone twinning, dichroism, and internal crystal strain are some of the properties …
How to Test for Diffusion Treated Gems
Step 3: Practical Gemology Lesson 16 Back to syllabus Since diffusion treated gems are so common, gemologists must learn how to identify these…
Ultraviolet Testing and Gemstone Identification
Gemstone identification typically starts with measuring a specimen’s refractive index (RI) and specific gravity (SG). These two tests…
Gemstone Magnetism: The Forgotten Property
Although gemstone magnetism isn’t a commonly tested gemstone property, it may be useful for making quick separations outside the lab. By Richard…
Gemstone Optical Properties
We tend to take light for granted. It’s such a common thing we experience every day. Rarely do we think of the scientific definition of light…
A Beginner’s Guide To Common Gemstone Heat Treatments
Gemstone heat treatments can turn mediocre pieces into items of great beauty. Heating a gem to a specific temperature and then cooling it is a common…
HPHT Diamond Update
Step 2: Advanced Gemology Lesson 8 Back to syllabus In 1999, General Electric (GE) introduced a new diamond treatment into the jewelry trade. The…
Natural Rubies Clarity Enhanced with Leaded Glass
Prior to 2006, most lead glass filled rubies contained only a very small percentage of glass in surface-reaching fractures to improve clarity.…
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