Gemstone weight is commonly measured in carats, where one carat equals 200 milligrams. This unit helps determine the size and value of gemstones, as larger stones are often rarer and more valuable. The weight of a gemstone can influence its appearance, but it is not the only factor that affects its overall value. When purchasing gemstones, it's important to consider both weight and other characteristics, such as clarity, color, and cut. These factors, along with the gemstone weight, contribute to the overall quality and desirability of the stone, impacting its market price.