Stones

You’ll also commonly find gems divided into two other categories: diamonds and colored stones. All gems other than diamonds fall into the “colored stones” category.

Gems are classified as Natural, Synthetic and Imitation
Natural stones form in nature synthetic stones are grown in laboratories.

Natural and synthetic materials can share the same properties yet still have considerable differences.

Natural gem takes millions of years to form comparing to mass-produced synthetic one. Since natural gemstones are rarer with unique aesthetic qualities are much more valuable than their synthetic counterparts.  Another approach to gem classification is to separate them into organics such as amber or pearl, coral and ivory.

The vast majority of gems are minerals. Diamond i.e., has the simplest chemical makeup. Also, many minerals are colorless.

Impurities give them color. A bit of chromium makes rubies, a bit of titanium and iron make blue sapphires, a touch of chromium make an emerald, a bit of iron and you get an aquamarine. Just a tiny number of impurities can make a mineral exceptionally valuable.

Another very common mineral species is quartz with colored varieties such as amethyst, citrine and smoky quartz.

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 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.