The mining of blue zoisite started in the east African country of Tanzania in the 1960s. In 1967, Mr. Henry B. Platt, then president of Tiffany & Co. of the United States, named this beautiful blue zoisite “tanzanite” in honor of its country of origin, and gradually popularized it through an aggressive sales promotion. With increases in production quality since 1989, prices have become affordable, and today more tanzanite is seen on the world market.

Incidentally, Kenya, also in eastern Africa, has been producing tsavorite (green grossular garnet) since the late 1960s. The region also produces materials such as fancy sapphire, ruby, emerald, and rhodolite garnet. Along with the Afghanistan / Pakistan region and China, eastern Africa is anticipated to become one of the three most important new gemstone-mining areas of the 21st century.

Tanzanite has a very attractive blue color that contains some purple. A distinct purplish hue can be seen in the photograph to the next page. Different from the “royal” blue of sapphire, this blue contains a very slight reddish hue, and could be described as “plum” blue. Tanzanite is a representative example of a stone showing the property of pleochroism. Pleochroism causes different colors to be seen when a stone is viewed from different angles; in the case of tanzanite, blue, purplish red, and light greenish yellow or brown are seen. When viewed face-up, these three colors combine to appear as the typical tanzanite color.

Starting with sapphire, there are many blue gemstones in the market- including fancy blue diamond, indicolite (blue tourmaline), aquamarine, lapis lazuli, and turquoise. Of the blue gemstones that are faceted, extremely beautiful tanzanites with a dark blue color and high transparency can be found relatively easily, with prices markedly lower than those of sapphires with similar beauty.

However, tanzanite has a hardness of 6 to 7, making its durability slightly less than ideal when compared to the hardness standard of 7 for quartz. Because of this, demand relative to production is low compared to that f sapphire.