Jewelers should tell you whether gemstone you’re considering has been treated when: treatment is not permanent; treated stone requires special care; or treatment significantly affects value of gemstone.

Some common treatments that you may be told about and their effects include: • Heating can lighten, darken or change color of some gems, or improve a gemstone’s clarity. • 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 gemstones’ clarity and appearance. • Fracture filling hides cracks or fractures in gems by injecting colorless plastic or glass into cracks and improves gemstones’ appearance and durability. • Diffusion treatment adds color to surface of colorless gems; center of stone remains colorless. • Dyeing adds color and improves color uniformity in some gemstones and pearls. • Bleaching lightens and whitens some gems, including jade and pearls.

Some diamonds may be treated to improve their appearance in similar ways as other gemstones. Since these treatments improve clarity of diamond, some jewelers refer to them as clarity enhancement. One type of treatment - fracture filling - conceals cracks in diamonds by filling them with a foreign substance. This filling may not be permanent and jewelers should tell you if diamond you’re considering has been fracture-filled.

Another treatment - lasering - involves use of a laser beam to improve appearance of diamonds that have black inclusions or pots. A laser beam is aimed at inclusion. Acid is then forced through a tiny tunnel made by laser beam to remove inclusion. Lasering is permanent and a laser-drilled stone does not require special care.

While a laser-drilled diamond may appear as beautiful as a comparable untreated stone, it may not be as valuable. That’s because an untreated stone of same quality is rarer and therefore more valuable. Jewelers should tell you whether diamond you’re considering has been laser-drilled.

Imitation diamonds, such as cubic zirconia, resemble diamonds in appearance but are much less costly. Certain laboratory created gemstones, such as lab-created moissanite, also resemble diamonds and may not be adequately detected by instruments originally used to identify cubic zirconia. Ask your jeweler if he has current testing equipment to distinguish between diamonds and other lab-created stones.