Millions of years in the making, tanzanite gemstones are relatively new to the gemstone-loving world. They were discovered in 1967 in Tanzania and instantly prized for their mesmerizing hues and color-changing effect. Tanzanite gems are deeply rich in color. When treated with heat and cut, tanzanite displays two colors: sapphire blue and deep purple. These colors alternate depending on the viewing angle and lighting conditions. Tanzanite is December's birthstone, making tanzanite jewelry an amazing way to celebrate a December birthday.