The price per carat of tanzanite can vary from a few dollars to thousands based on the clarity, color and cut of the stone. Inclusions, or interior impurities, and blemishes, or exterior impurities, affect the value of individual stones. If a gemstone is clean, meaning there are no visible inclusions or blemishes, then it is valued higher than a stone with either or both. However, if the inclusion does not impede the brilliance of the tanzanite, then it doesn't decrease the value by much.
Stones that display a higher saturation of color are valued higher than those with less depth. A deep blue tone with good depth in the gemstone is rare, making it a valuable characteristic of tanzanite.
Cut is another major factor in grading stones for price. The goal of cutting stones is to maximize their luminescence, usually via facets. When a skilled jeweler has cut a quality stone with many well-placed and well-cut facets, it displays maximum brilliance. These stones garner a higher price.
Along with the cut of the stone goes its shape and polish. A stone should be well-polished with no scratches. Round stones tend to be more expensive, as more raw material is lost during the cutting process.Learn more about Precious Metals & Gems