What is the carat for pure diamond?

When talking about diamonds and other gemstones, carats is a measure of their weight. One carat is equal to 200mg. Other factors such as colour, flaws and quality of cut will have a big effect on the cost. A large diamond may be of poor quality and therefore cheaper than some smaller diamonds with better characteristics.

Another Answer

All diamonds are 'pure diamond' regardless of their carat weight. Gold, however, does have a purity indicator: karat.

(Also, all carrots are pure carrots.)