Unlike gemstones mined throughout the globe, Tanzanite comes from a single source that is located in Tanzania, Africa and in close proximity to Mount Kilimanjaro. Even Tiffany refers to Tanzanite gems as “the most beautiful blue stone discovered in 2000 years,” which is why they so often end up in museums or being owned by avid collectors and investors.

Due to the comparative rarity of these stones and the fact that they’re relatively new to the market, Tanzanite may be harder to find than other December birthstones. These gems only hit commercial markets in the 1960s, but from the moment they debuted, they have been superstars.