A craftsman must expertly cut a diamond so that light will reflect from mirror-like facets and disperse through the top of the stone. The result is referred to as the diamond s brilliance or fire . A diamond that is cut too thin or too thick is considered miscut. These stones lose light as it spills through the bottom or sides. Miscut diamonds are less brilliant and eye catching, and therefore are less valuable, placing lower on the pyramid.
Microscopes reveal flaws.
Practically all diamonds have identifying characteristics that are invisible to the naked eye. Only under a 10-magnification jewelers microscope can these inclusions be seen. Inclusions, or imperfections, can be carbon spots or feathers. These are considered nature s birthmarks. Diamonds with inclusions that cannot be seen by the naked eye are rated SI slight imperfection.