---
title: "Gem species: meaning in gemology"
description: "A gem species is a mineral with one chemical composition and one crystal structure, such as corundum, beryl or quartz."
url: https://digitalgemology.com/learn/glossary/gem-species
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Colored gemstones

# Gem species

Also called mineral species, species

A gem species is a mineral with one chemical composition and one crystal structure, such as corundum, beryl or quartz.

## In more detail

The species sets the optical and physical properties: refractive index, hardness and specific gravity. Ruby and blue sapphire share the refractive indices of corundum, but not their color. A species can have many varieties.

## On a grading report

Report layouts differ. Some labs print the mineral as 'Identification' and the variety name, such as ruby, under 'Species'.

## Related terms

- [Gem variety](https://digitalgemology.com/learn/glossary/gem-variety): A variety is a subdivision of a gem species, usually by color. Ruby and sapphire are varieties of corundum, and emerald is a variety of beryl.
- [Corundum](https://digitalgemology.com/learn/glossary/corundum): Corundum is the mineral species made only of aluminum and oxygen. Its red variety is ruby, and all its other colors are sapphire.
- [Beryl](https://digitalgemology.com/learn/glossary/beryl): Beryl is the mineral species of emerald. Aquamarine and the other beryl colors belong to the same species.
- [Quartz](https://digitalgemology.com/learn/glossary/quartz): Quartz is the mineral species of amethyst and citrine. It is silicon dioxide in a trigonal crystal.
- [Crystal system](https://digitalgemology.com/learn/glossary/crystal-system): A crystal system groups crystals by the symmetry of their atomic structure. Gemologists use seven: cubic, tetragonal, hexagonal, trigonal, orthorhombic, monoclinic and triclinic.

## Learn more

- [Dichroscope](https://digitalgemology.com/about/how-we-measure/dichroscope)

[All 328 terms](https://digitalgemology.com/learn/glossary)