Hardness: 6.5

Although tanzanite is a relative newcomer to the gemstone market, it has made its mark on the jewelry world in a hurry. In fact, no recent gemstone discovery has had more of an impact.

This rare, exotic gem was first discovered by Portuguese prospector Manuel d'Souza in the Merelani Hills of Tanzania in 1967, in the shadow of majestic Mount Kilimanjaro. This breathtaking location is the only known mining site on earth for tanzanite. The stone was named after its country of origin by Tiffany & Co. in New York. The world-renowned jeweler first introduced tanzanite to the market in 1969 and began to aggressively market it to the public in the 1980s.

Tanzanite, a variety of the mineral zoisite, occurs in a wide range of shapes, sizes and colors. Rarely pure blue, the gem almost always displays signature overtones of purple. In smaller sizes, it tends toward lighter tones, with lavender the most common. In larger sizes, the gem typically displays deeper, richer blues and purples.

In its natural form, tanzanite is typically brown with reddish, orange, yellow or bronze hues. Heat treatment releases the spectacular violet-blue colors the stone is known for.

The finest quality tanzanite is usually deep blue or violet, with few, if any, inclusions visible under magnification. Such stones are also exceptionally well-cut and polished. But color is the most important factor to consider when buying tanzanite.

Tanzanite is similar in hardness to an emerald but softer than a diamond. Clean your tanzanite with warm, soapy water and a soft bristle brush. Also, avoid ultrasonic or steam cleaning, because the high temperatures could damage the stone. Most nicks and scratches can be removed through polishing.