In the last 10 years or so, tanzanite has taken the gem world by storm. Mined only in Tanzania, Africa, tanzanite was first discovered in 1967. It's brilliant periwinkle-blue color makes any outfit pop. Other variations of the colors of tanzanite are violet-blue and blue with dark purple undertones. The saturation of color usually depends on the size of the stone. The larger the stone, the deeper the violet-blue color. Tanzanite is a fairly hard stone. On the Mohs Scale of Hardness, tanzanite comes in at 6.5-7.0. December babies can be delighted in knowing that tanzanite is now an alternate birthstone for them.