Rubylike gemstone

• Gemstone often passed off as a ruby
• Mineral used as a gem
• Ruby ___ (gem)
• Crystalline gemstone
• Gemstone mined in Sri Lanka
• A hard glassy mineral consisting of an oxide of magnesium and aluminum
• Occurs in various colors that are used as gemstones
• Mineral containing magnesium

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.

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Spinel \Spi*nel"\, Spinelle \Spi*nelle"\, n. [F. spinelle, or LL. spinellus, perhaps from L. spina a thorn, a prickle, in allusion to its pointed crystals.] (Min.) A mineral occuring in octahedrons of great hardness and various colors, as red, green, blue, ...