When shopping for jewelry, it's not unusual to start wondering what the difference is between a Carat and a Karat. Both the terms are used for the purpose of measurement. The term 'Carat' refers to the weight of a diamond. It is derived from the carob seeds, which are remarkably consistent in weight and shape and so were the favored scale balances in ancient times. This was standardized in 1907 and after that 1 carat became 0.2 grams or 1/142 of an ounce. Furthermore, each carat is divided into 100 points. Therefore, 1/4 carat diamond is considered as 25 points and 1/2 carat diamond is considered as 50 points and so on. Carat is also used in its abbreviated 'Ct' form. On the other hand, a 'Karat' is a measurement used to measure the purity of gold, with 24 karat being the purest. The measurement gauges how much gold vs. how much alloy is in the piece of jewelry. If a jewelry item contains 18 Karat Gold that means it has Eighteen Parts Pure Gold and Six Parts Other Metal Alloys. Karat is also used in its abbreviated 'kt' form.