The term 'JEWELER's Unit' refers to three different units of measurement used in the jewelry industry. The first is Karat, which is a unit of measure for the purity of gold alloys, and is abbreviated as 'K'. The second is Pennyweight, which is a unit of measure for the weight of precious metals, and is abbreviated as 'dwt'. The third is CARAT, which is a unit of measure for the weight of gemstones, and is abbreviated as 'ct'. All three of these units are commonly used by jewelers when assessing the quality and value of jewelry.