First discovered in the late 1960s in the foothills of Mount Kilimanjaro, Tanzanite was originally believed to have little value and was immediately thrown out. Today, they are some of the rarest stones in the world and can be sourced from a single mine in the Merelani Hills of Tanzania. Unheated ‘Fancy’ Tanzanites are highly desired and come in a broad range of colors, from deep blue and violet to burgundy and yellow.