Garnet and is one of the most prized of garnet varieties. Topazolite is a golden-yellow variety and melanite is a black variety. Grossular is a calcium-aluminium garnet with the formula CaAl(SiO), though the calcium may in part be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from the botanical name for the gooseberry, "grossularia", in reference to the green garnet of this composition that is found in Siberia. Other shades include cinnamon brown (cinnamon stone variety), red, and yellow. Because of its inferior hardness to zircon, which the yellow crystals resemble, they have also
Gemstone irradiation enabled the creation of gemstone colors that do not exist or are extremely rare in nature. The term "irradiation" is a very broad one, which covers bombardment by subatomic particles as well as the use of the full range of electromagnetic radiation, including (in order of increasing frequency and decreasing wavelength) infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. Certain natural gemstone colors, such as blue-to-green colors in diamonds, are the results of the exposure to natural radiation in the earth, which is usually alpha or beta particle. The limited penetrating ability of these particles result in partial