Opal Specialist Mini Course
Opal Buying Guide
Opal Grading and Terminology
Our IGS opal price guide uses a grading system unique to opals. You can find a full explanation of this system and its terminology in our article on appraising opals. Here’s a brief review:
- Opals have grades of below commercial, commercial, good, fine, and extra fine. These assessments cover an opal’s colors, directionality of flashes, imperfections, and cut.
- Body tones, from N1 (black) to N9 (white), describe the base color of a stone, without play of color. Gemologists use this system to distinguish black, dark, light, and white opals. Stones from N1 to N4 are considered black opals. N5 to N6 are considered dark opals. N7 to N8 are considered light opals. An N9 is considered a white opal.
Opal Buying and the Four Cs
Opals can still be evaluated in terms of color, clarity, cut, and carat. However, to properly judge their value, you have to consider some factors unique to these gemstones.
Color is the most import factor for evaluating an opal’s value. You must consider the number of colors present, the clarity of colors, the brightness of fire, and the play-of-color…
Donald Clark, CSM IMG
The late Donald Clark, CSM founded the International Gem Society in 1998. Donald started in the gem and jewelry industry in 1976. He received his formal gemology training from the Gemological Institute of America (GIA) and the American Society of Gemcutters (ASG). The letters “CSM” after his name stood for Certified Supreme Master Gemcutter, a designation of Wykoff’s ASG which has often been referred to as the doctorate of gem cutting. The American Society of Gemcutters only had 54 people reach this level. Along with dozens of articles for leading trade magazines, Donald authored the book “Modern Faceting, the Easy Way.”
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