A member of the Zoisite family, tanzanite is the newest official birthstone.
The first selected after 95 years the vote was finalized in November 2002.
It was chosen to represent the month of December, symbolizing prosperity. The unusual gem is a beautiful rich deep purplish blue with exceptional
pleochroism. When crystal is rotated it will exhibit up to three distinct color
changes.
First discovered in March of 1966 by an Arusha tailor named Sousa at still the only known deposit, a place later known as the Merelani Mine of Northern Tanzania. It was first thought to be a sapphire but after closer examination with proper gem identification equipment, it was discovered to be an unusual form of zoisite. It became a world wide new gem
sensation with the help of Tiffany & Co., who created a vigorous sales campaign in 1967 calling the gem by its country of origin, "Tanzanite." Most natural stones are gray or brown but additional colors of violet, blue, reddish-purple, green, light green,
and white plus a completely transparent shade are also likely to appear in the heavily metamorphosed zone of tough layered rock.
Most stones that do not exhibit the typical deep blue, purple-violet tones are heat treated to increase color
saturation. A rule of thumb, the deeper and more intense the color the more expensive per carat the stone will be. It is somewhat unusual to see stones of four carats or more with uniform color. The largest finished flawless gem found to date is housed in the Smithsonian Institution's Gem Collection weighting in at 122.7 carats of deep color intensity. It was originally recommended to not be worn in rings because of its relatively mild hardness.
