Garnets are a set of closely related minerals that form a group, resulting in gemstones in almost every colour. Red garnets have a long history, but modern gem buyers can pick from an opulent palette of garnet colours: greens, oranges, pinkish oranges, intensely saturated purplish reds, and even some blues. All garnets have essentially the same crystal structure, but they vary in chemical composition. There are more than twenty garnet categories, called species, but only five are commercially important as gems. Garnet is the birthstone for January and the gem for the 2nd anniversary.