- Knife-edge Girdle
- A girdle of a diamond that is so thin that it can be likened to the edge of a sharp knife. Since such a girdle is easily chipped, an ideal girdle has an appreciable thickness.
- (a) An included diamond crystal that is encountered at the surface of a stone during the polishing operation, and that stands out as a small, raised surface on the finished stone. (b) An included diamond crystal that is encountered by the saw blade. Since the softest directions available for sawing and polishing are used by the cutter, and since included crystals have a different orientation from the surrounding mass, they almost always have a harder direction than that being exploited. (c) A small section of a twinned stone in which the grain differs from the main mass.