Step 4: Gem Grading

Lesson 3

In recent decades, something remarkable invaded the thinking process of the colored stone industry. From dealers to consumers, they all discovered “The Cut.” Promotional literature and gemological thinking had long regarded gemstone cutting as a mere equal among the four Cs. However, more than any of the other qualities, the cut holds the key to gemological success. Gemstone cutting deserves an objective system of evaluation. Therefore, I’ve created the Five Ps as a way to communicate the properties of a cut.

The Role of Nature in Gem Evaluation

Even a cursory review of color, clarity, and carat and their functions reveals that Nature bestows these qualities on gems. We have little control over them.


What is gemstone color but a visual demonstration of contamination? Trace amounts of visiting chemicals create an exciting array of gem colors. Take the mineral corundum, for example. Add sufficient chromium and the great, grand ruby emerges. Then, add iron oxide and luscious sapphire arises. That same iron oxide added to the mineral beryl produces aquamarine. But add that same chromium to beryl and you get a shimmering emerald. These awesome transformations…