Round Cut Black Diamond is the world's most popular and traditional diamond shape for black diamond jewelry. The round cut is a symbol of commitment. They have an asymmetrical shape that consists of 58 facets. Why is round brilliant cut so popular? Then, let me tell you because a brilliant-cut black diamond ability to optimize light reflection makes it brighter and more brilliant than all other shape diamond. Round cut diamonds carry the largest premium for two reasons: demand and rough wastage.