Step 1: Introduction to Gemology

Lesson 6

Little is simple and straightforward in gemology. Every established principle has an exception. This applies to gem classification as well. There isn’t one way to classify gemstones. Rather, there are several. Each has its own purpose as well as exceptions that warrant close attention.

Precious and Semiprecious Gems

For centuries, people have used the terms precious and semiprecious to describe gemstones. You’ll still occasionally hear these terms today. However, this gem classification has so many exceptions it has no real value. For example, diamonds have traditionally been considered precious gems, yet some sell for $100 a carat. You can see them (with sufficient magnification) as accent stones on inexpensive jewelry. On the other hand, garnet gems have traditionally been considered semiprecious gems, yet some sell in excess of $1,000 a carat, ten times the price of a low-quality diamond.

Referring to a set of gem types as “precious” and all other gems as “semiprecious” can be misleading, since it implies precious stones have inherently greater value. Professional gemologists no longer use these terms. Consumers, be wary if you encounter these descriptions.

Diamonds and Colored Stones

Gems are also divided…