Naturally black diamonds are extremely rare and can have a very high value, depending on the cut, color, clarity and carat size of the diamond. The most accurate way to learn the value of a black diamond is to have it ap... More »

"Alaska black diamonds" is the trade name of a mineralized form of iron oxide known as hematite. Hematite occurs around the world, and the milled gemstones created from it hold a lustrous black finish. Hematite has been ... More »

Diamonds are worn as jewelry and used in a variety of industrial applications. Diamond is the hardest natural substance in the world, and stones that are too small or do not have the requisite quality for jewelry mountin... More »

To determine the value of a diamond, note its color, clarity, cut and carat. Diamonds are more valuable when they have less color, lack spots and imperfections, have higher cut grades and weigh more. Compare each of thes... More »

Determining the quality of a diamond involves the consideration of its cut, clarity, color, carat size and certification. Certification through an accredited organization, such as the American Gem Society or the Gemologi... More »

As with other gems, the value per carat of tanzanite is influenced by color, cut and clarity. Other factors jewelers use to grade tanzanite include shape and polish. More »

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Four aspects of gemstone grading determine the per-carat value of a ruby, including color, clarity, cut and carat. Quality of a top-grade ruby means it has rare features, rather than being labelled as better than another... More »