For example, a half-carat gemstone would weigh .50 carats or 50 points. Gemstone treatments or enhancements refer to the way some gems are treated to improve their appearance or durability, or even change their color. Many gemstones are treated in some way. The effects of some treatments may lessen or change over time and some treated stones may require special care. Some enhancements also affect the value of a stone, when measured against a comparable untreated stone.
Irradiation can add more color to colored diamonds, certain other gemstones and pearls.
Impregnating some gems with colorless oils, wax or resins makes a variety of imperfections less visible and can improve the gemstones' clarity and appearance. Fracture filling hides cracks or fractures in gems by injecting colorless plastic or glass into the cracks and improves the gemstones' appearance and durability. Dyeing adds color and improves color uniformity in some gemstones and pearls. Bleaching lightens and whitens some gems, including jade and pearls. The clarity and color of a diamond usually are graded.