To find the value of gemstones, first use an electronic microbalance scale to weigh the gem and determine the carat. Next, use an optical measuring device to measure proportions, facet angles, the cut of the stone, and how it reflects and refracts light. Next, determine the grade of the gem as it pertains to color and clarity. The value depends on these factors, as well as the rarity of the stone.Continue Reading
Determine the color value based on the hue, tone and saturation of the stone, which varies depending on the gem type. Grade each of these from one to 10, where 10 is the highest possible color grade. The more cloudy or flawed a stone is, the lower the rating. Determine the clarity, or degree of imperfections, as a Type I, Type II or Type III, depending on the type of stone it is. Next, score the clarity on a scale from one to three.
Have these values corroborated by another jeweler. Once verified and documented, determine the rarity of the type of stone. Because diamonds are more rare than many other gems, the value of diamonds is higher. Gems with better ratings on cut, color and clarity, in addition to higher carat weight, are more valuable.Learn more about Precious Metals & Gems