The tanzanite we know today is a modern discovery involving a Masai tribesman who stumbled upon it in 1967. Today, the gem is commercially mined only in one place on earth in Tanzania, where it gets its name from. This makes tanzanite rarer than diamonds! The gem also derives its value from its exceptional midnight to violetish blue color. Tanzanite is a birthstone for December and the gem for the 24th anniversary.