Suzanne Holvey, age 11, of Eugene, Ore., for her question:

What is a karat?

This word may be spelled karat or carat and is pronounced like the carrot vegetable. The original carat was borrowed from a bean to name a unit of weight. The measurement was originated by the Arabs. Their word carat meant a bean or seed, and they estimated their precious gem stones by carats or bean weights.

The modern carat is a weight unit of 200 milligrams of the metric system. The ounce of our weight system equals a little more than 28.33 grams, and one gram equals five carat units. The carat also is used to measure the quality of golden objects. Pure gold is 24 carats fine, but it is soft and usually hardened with alloy metals. The alloy also is figured in 24 parts, but only the parts of pure gold are called carats. In l8 caret gold there are l8 parts of gold and six parts of alloy metal.