mineral

Ruby (in costume jewelry context)

Corundum (Al2O3) with Chromium impurities

Hardness: 9 on Mohs scale; Color: Red (ranging from pinkish to pigeon-blood); Luster: Adamantine to vitreous; Crystal structure: Trigonal; Cleavage: None (has parting); Specific gravity: 3.97–4.05.

Hardness: 9 on Mohs scale
Color: Red (ranging from pinkish to pigeon-blood)
Luster: Adamantine to vitreous

Identified March 29, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 9 on Mohs scale; Color: Red (ranging from pinkish to pigeon-blood); Luster: Adamantine to vitreous; Crystal structure: Trigonal; Cleavage: None (has parting); Specific gravity: 3.97–4.05.

Formation & geological history

Formed in metamorphic rocks (schist or gneiss) or marble, and sometimes in igneous rocks. While natural rubies are millions of years old, synthetic versions found in modern jewelry are created via the Verneuil flame fusion or flux growth processes.

Uses & applications

Primary use in high-end jewelry (natural) or costume jewelry and precision instruments/lasers (synthetic).

Geological facts

Ruby is the birthstone for July. Fine rubies can be more valuable than diamonds of the same weight. If synthetic, it shares the exact chemical properties of natural ruby but is created in a lab.

Field identification & locations

Identify by its intense red color and hardness. In the field, look for hexagonal prismatic crystals in marble or basalt. In jewelry, determine if it is natural or synthetic by looking for inclusions under a jeweler's loupe; flawless appearance often suggests synthetic manufacture.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral