Most colored stones are sold by which measurement?

The correct choice is weight, as most colored stones are typically sold based on their carat weight. Carat weight is a universal measurement used in the gemstone industry that directly correlates to the size and value of the stone. Generally, larger gemstones weigh more and are rarer, which can significantly elevate their market price. While size, color, and diameter are important characteristics that influence the desirability and price of a colored stone, weight remains the most standard metric for pricing in the industry.

For example, two stones of the same type may look similar in color and size but could differ greatly in value based on their weight. Thus, weight serves as a critical determinant in both the sale of colored stones and in evaluating their overall worth, reinforcing why this is the accepted standard in the marketplace.