100 Gems - December birthstone tanzanite

Tanzania is the only known source of tanzanite, a blue-violet zoisite variety first identified in the Merelani Hills near Arusha in 1967 and subsequently named and commercialized by Tiffany & Co. The stone's scarcity — the mineralized zone spans roughly 7 square kilometers — is what makes it a reasonable subject for a commemorative issue from the country that controls its entire supply.

The December birthstone designation came from a 2002 revision to the American Gem Trade Association's official list, making tanzanite one of the more recently added birthstones to any such calendar — a detail that gives the thematic framing here a fairly short history.