Occurs in various colors that are used as gemstones

• Mineral containing magnesium
• Reddish mineral
• Rubylike gem
• Mineral used as a gem
• A hard glassy mineral consisting of an oxide of magnesium and aluminum
• Gemstone often passed off as a ruby
• Crystalline gemstone

WordNet Word definitions in WordNet
n. a hard glassy mineral consisting of an oxide of magnesium and aluminum; occurs in various colors that are used as gemstones

Wiktionary Word definitions in Wiktionary
n. (context mineralogy English) Any of several hard minerals of cubic symmetry that are mixed oxides of magnesium and aluminium and are used as gemstones of various colours.