Garnet, a hard, transparent or semi-transparent mineral occurring as crystals, as grains, or in irregular masses. Garnets are silicates in combination with iron, calcium, manganese, magnesium, aluminum, or chromium. Most of the gem garnets —pyrope, almandite, spessartite, andradite, uvarovite, and grossularite—are reddish in color, but some are greenish, yellowish, or white. The garnet is the birthstone for January and represents constancy. Common garnets are used as watch jewels (bearings), as abrasives, and in coating sandpaper.