December’s birthstones offer three ways to fight the winter blues: tanzanite, zircon, and turquoise—all of them, appropriately, best known for beautiful shades of blue.  These gemstones range from the oldest on Earth (zircon), to one of the first mined and used in jewelry (turquoise), to one of the most recently discovered Tanzanite.  Unlike many well-known gemstones that have been in use for centuries, tanzanite’s history is relatively modern.

The common story of tanzanite’s discovery tells of Maasai herders who found blue crystals in the Merelani Hills near Arusha, Tanzania, while tending livestock in 1967. They notified a prospector named Manuel d’Souza, who promptly registered claims with the government to begin mining.

Initially, d’Souza thought he was mining sapphire, but the crystal was soon identified as a vibrant blue variety of zoisite—a mineral that had been around since the early 1800s.

Tiffany & Co. recognized this blue gem’s potential to rival more expensive sapphire and agreed to become its main distributor. Instead of publicizing “blue zoisite” —which sounded a little too much like “suicide” —Tiffany named the gemstone “tanzanite” to highlight its exclusive geographic origin and introduced it with a promotional campaign in 1968.