Table of Gems Ordered by Crystal System

The gems are sorted by their crystal system: isometric (cubic), tetragonal, hexagonal, trigonal, orthorhombic, monoclinic, and triclinic.

Amorphous gems have no crystal structure.

Selected Minerals by Crystal System

Notes

1. Boleite has also been classed as a tetragonal, pseudo-cubic crystal.

2. Synthetic, lab-created material.

3. May lose their crystalline structure due to natural radiation (metamictization).

4. In modern times, hyacinth or jacinth usually refers to reddish brown zircon, which belongs to the tetragonal crystal system. However, historically it has also been used to refer to hessonite (cubic), topazes (orthorhombic), and various other gemstones.

5. Mimetite has also been classed as a monoclinic, pseudo-hexagonal crystal.

6. Both natural and synthetic stones. (Natural moissanite crystals are too small to cut).

7. Any beryl variety not aquamarine, emerald, goshenite, heliodor, morganite, or red.

8. Many of the materials mineralogists have classed as trigonal crystals have been classed by gemologists as hexagonal crystals in a trigonal subclass. Thus, you'll find many of the gems listed here classed as hexagonal in their individual gem listings.

9. Wollastonite has monoclinic and triclinic polytypes.

Additional Crystal System Information

For more detailed information, consult the individual gem listings as well as these International Gem Society articles:

What are Crystal Systems and Mineral Habits?

Descriptive Crystallography for Gemologists

What is Crystallography?