Tanzanites were discovered in 1967 and only appear in one location in the world: a four square kilometre area in the foothills of Mount Kilimanjaro. Since they only have one global source, they're considered one of the rarest gems on Earth. Yes, they are far rarer than even Diamonds! It is estimated that we will exhaust the world's supply of Tanzanite within two decades, which some believe will cause their value to increase exponentially. They are stunning gems, which can look Blue or Violet depending on the direction you view them in. Learn more.