The cut of a gemstone is one of the most important factors in determining how much sparkle a gemstone produces. Depth is the height of a gemstone measured from the culet to the table. Depth percentage is the height of a gemstone, measured from the culet to the table, divided by the width of the gemstone. The depth percentage is critical to creating brilliance and fire in a diamond. A gemstone with a depth percentage too low or too high will lack sparkle.
Facet is the flat, polished surface on a diamond.
A round, full-cut diamond usually has 58 facets. Fancy Shape are any shape except rounds. A pear shape is an example of a fancy shape. Sometimes fancy shapes are simply called fancies. Feathers are cracks of various sizes.