Gemstone Color Measurements and Specifications
Gemstone color measurements are hard to make with conventional color-order systems. Learn how recent colorimetry tech advances have improved…
What is a Gem?
Even the most general definition of a gem has many exceptions. Learn what qualities have been used to identify gemstones both scientifically and…
Phenomenal Gems: Cat’s Eyes, Star Stones, and More
Phenomenal gems seem to do magical things with light. Learn the science behind optical effects like cat’s eyes and star stones and how to judge…
Aquamarine Value, Price, and Jewelry Information
Named after the color of sea water, aquamarine is the blue to blue-green member of the beryl family. Readily available and moderately priced, the…
Scapolite Value, Price, and Jewelry Information
Although not well known, scapolite would make an attractive gem material for both jewelry enthusiasts and mineral collectors. It comes in a wide…
The Usambara Effect
The Usambara effect is the term applied to a type of color change in gemstones, first seen in tourmalines from the Umba Valley in Tanzania. However,…
Faceting Tips for Exotic Gemstones
Some gems are seldom faceted because they’re rarely found in nature or rarely used for jewelry. Learn a few tricks for faceting seven exotic gemstones.…
What is the Usambara Effect In Gemstones?
The Usambara effect is a gemstone color change phenomenon distinct from pleochroism or the alexandrite effect. Tourmaline and other species…
Destructive Testing with a Streak Plate
Step 3: Practical Gemology Lesson 20 Back to syllabus Gemstone streak testing is fun, if you have rough material to spare. It’s not recommended…
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