GIA’s pictorial example of carat weight
GIA’s carat weight pictorial diagram
Materials and images kindly provided by the Gemological Institute of America – GIA
Click images for larger view
Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip.
Because even a fraction of a carat can make a considerable difference in cost, precision is crucial. In the diamond industry, weight is often measured to the hundred thousandths of a carat, and rounded to a hundredth of a carat.