What Does the L/W Ratio Mean in Gem Cutting?
Gem cutters use the “length-to-width” or L/W ratio to determine how to cut rough gems. Learn how to choose gem designs based on a stone’s L/W…
Identifying Synthetic Gems
Distinguishing natural from synthetic gems is a critical skill for gemologists. It could mean the difference between valuing a gemstone at thousands…
Phenomenal Gems – Unique Phenomena in Gemstones
Some optical effects in gemstones, such as color, brilliance, and dispersion, can be quite impressive. However, not all optical effects are considered…
Basic Gem Appraisal Terms: What is Value?
Step 6: Appraising Lesson 1 Back to syllabus Many people assume that a jewelry or gem appraisal sets a definitive price for an item. Actually, the…
Appraising Gems and Jewelry
Step 6: Appraising Lesson 2 Back to syllabus Appraising gems and jewelry involves giving an opinion of value. If you take a pair of earrings to a jewelry…
Evaluating Gemstone Cutting: The Five Ps
Step 4: Gem Grading Lesson 3 Back to syllabus In recent decades, something remarkable invaded the thinking process of the colored stone industry.…
Recutting Diamonds and Colored Gemstones
As a professional gemologist, you’ll grade and value gems. Occasionally, you’ll come across a stone that may need recutting. However,…
Evaluating Gem Color: Hue, Tone, and Saturation
What color is the gem on the left? If you answered red, you’re wrong. It’s orange. Most people think the color of the gem on the right…
Clarity Grading for Colored Gemstones
Don’t underestimate the importance of clarity, one of the Four Cs of gemstone grading. For faceted gems, basic clarity grading involves…
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