Carat (mass) Despite its being a non-metric unit, a number of metric countries have used this unit for its limited range of application. The Board of Trade carat was divisible into four "diamond grains", but measurements were typically made in multiples of carat. There were also two varieties of "refiners' carats" once used in the United Kingdom — the pound carat and the ounce carat. The pound troy was divisible into 24 "pound carats" of 240 grains troy each; the pound carat was divisible into four "pound grains" of 60 grains troy each; and the pound grain was divisible into four "pound
Gold-filled jewelry Gold-filled jewelry Gold-filled jewelry is jewelry composed of a solid layer of gold (typically constituting at least 5% of the item's total weight) mechanically bonded to a base of either sterling silver or some base metal. The related terms "rolled gold plate" and "gold overlay" may legally be used in some contexts if the layer of gold constitutes less than 5% of the item's weight. Most high quality gold-filled pieces have the same appearance as high carat gold, and gold-filled items, even with daily wear, can last 10 to 30 years though the layer of gold will eventually wear off