Gemstones between 5.5 mm and 5.9 mm refer to stones or mineral inlays that can meet the requirements of jewelry after grinding and polishing. The specifications of a 35-cent square gem are between 5.5 mm and 5.9 mm. This precious ore is bright in color and high in hardness, and will not change under the action of atmosphere and chemicals. Can be used as instrument bearings, abrasives, decorations, etc. It also refers to precious stones.