Why is a Carat so named? Carob Beans and Carats
'The carat (ct) (not to be confused with the karat, sometimes spelled carat, a unit of purity of gold alloys), is a unit of mass equal to 200 mg (0.2 g; 0.007055 oz) and is used for measuring gemstones and pearls. The current definition, sometimes known as the metric carat, was adopted in 1907 at the Fourth General Conference on Weights and Measures and soon afterwards in many countries around the world'. Wikipedia
We found a Carob tree whilst on holiday and brought some pods home so that we could test how close to a carat they are, and it turns out that although they do vary (as has been found in scientific tests), they are pretty useful... more so than trying to judge a Diamond's weight by eye alone, and particularly so with the older more irregular cuts. In our quick experiment with this old 1.02ct Diamond the first chosen Carob seed weighed 1.01cts which we regarded as a reasonable success. We're not sure that we'll be using this method very often, but if you'd like to read more on the relationship between the Carob and Carat, the article listed below describes the results of tests which have been done to test their reliability.