Purple Gem Spinel from Vietnam and Afghanistan: Comparison of Trace Element Chemistry, Cause of Color, and Inclusions
Spinel: The mineral Spinel information and pictures
File:Pyrrhotite-Spinel-t08-03a.jpg - Wikimedia Commons
Spinel from Mahenge (Tanzania) and its Heat Treatment - SSEF
Spinel mineral information and data
Lapis lazuli - Wikipedia
Spinel: Red and blue gems confused with ruby and sapphire
Spinel Mineral Specimen For Sale
Spinel Supergroup: Mineral information, data and localities.
Spinel cluster - MUN16-37 - Pein Pyit - Burma Mineral Specimen
Spinel Gemstone
Spinel: Mineral information, data and localities.
Minerals, Free Full-Text
Canadian Arctic has all the mineral ingredients for prized blue gemstones
Spinel - Wikipedia