Your question is not clear. Is it referring to Diamond carat or Gold karat. This is because both have different meaning. While, Carat refers to weight of diamond (or gemstones), Karat refers to...
Your question implies that the number is less than one full carat, so you could also write it as .59 carat -- rounding up, meaning that the stone weighs just over half a carat.
Carat is the standard unit of weight to measure gemstones. One carat equals 200 milligrams; a 5-carat stone weighs 1 gram. The word carat originates from the Greek word kerátion, which means carob...