Gemstone treatments

Assembled Assembled Stones, Doublets and Triplets Assembled stones combine separate materials to imitate a single gem or enhance appearance. They must be disclosed. Opal, Garnet-topped doublets, Quartz doublets, Soud├®… Color Enhancement Dyeing Dyeing artificially improves color in porous or fractured materials. Durability varies and disclosure is required. Jadeite, Nephrite, Chalcedony, Agate, Turquoise, Coral,… Clarity Enhancement Flux Healing, Corundum Flux healing uses high temperature and flux to partially heal fractures in corundum. It improves apparent clarity and must be disclosed. Ruby and Sapphire Clarity Enhancement Fracture Filling, Corundum Fracture filling improves apparent clarity in corundum. Lead-glass-filled ruby is the most important commercial example, but other fillers can occur. Ruby and Sapphire Heat Heat Treatment, Aquamarine Heating aquamarine is common and stable. It improves color by reducing green or yellow components. Aquamarine and some Beryl Heat Heat Treatment, Beryl Heating is common in several beryl varieties to improve or stabilize color. It is usually stable but should be disclosed when known. Aquamarine, Morganite, Heliodor and other Beryl… Heat Heat Treatment, Corundum Heat is the most common corundum treatment. It can improve color and clarity, but unheated ruby and sapphire with fine color command a premium. Ruby and Sapphire Heat Heat Treatment, Quartz Heating is common in commercial citrine and other quartz colors. It changes color centers and iron-related coloration. Amethyst, Citrine, Ametrine, Smoky Quartz and… Heat Heat Treatment, Tanzanite Nearly all commercial tanzanite is heated. The treatment is stable and widely accepted. Tanzanite, Zoisite Heat Heat Treatment, Tourmaline Heat treatment is used to improve tourmaline color and is often stable. Disclosure is expected when known. Paraiba-type Tourmaline, Rubellite, Indicolite and other… Color Enhancement Irradiation and Annealing, Topaz Most blue topaz on the market is irradiated and annealed. The treatment is stable after proper safety decay and disclosure. Blue Topaz Color Enhancement Irradiation, Quartz Irradiation modifies quartz color centers. The result may imitate natural smoky quartz, citrine, or other commercial colors. Smoky Quartz, Amethyst, Citrine, Prasiolite and… Clarity Enhancement Oil Filling, Emerald Oiling is common in emerald and improves apparent clarity. Degree of filling matters: minor, moderate, or significant treatment affects value. Emerald Color Enhancement Smoke Treatment Smoke treatment darkens opal body color to imitate black opal or improve contrast. It must be disclosed. Opal, especially hydrophane opal Impregnation Stabilization Stabilization impregnates porous material with polymer to improve durability and sometimes color. It is common in turquoise. Turquoise, Opal, porous ornamental gems Color Enhancement Sugar-Acid Treatment, Opal Sugar and acid create carbon inside porous opal to darken the body. It can imitate more valuable black opal. Opal Surface Enhancement Surface Coating Coatings create color or optical effects on the surface only. They can be damaged by wear, polishing, or chemicals. Topaz, Quartz, Mystic Topaz, Azotic-coated gems,… Color Enhancement Bleaching Bleaching removes unwanted color or stains. Acceptance depends on gem type, extent, and market norms. Pearls, Coral, Jadeite, Ivory substitutes, porous… Color Enhancement Irradiation, Beryl Irradiation creates or modifies color centers in beryl. Stability depends on variety and color center type. Heliodor, Maxixe-type Beryl, some Morganite and… Composite Appearance Quench Crackling and Dyeing Thermal shock creates cracks that are then dyed to imitate more valuable or unusual gems. Quartz, Rock Crystal, low-cost decorative gems Surface Enhancement Waxing Waxing is a common minor surface enhancement. In jade it is often accepted when light, but heavy treatment should be disclosed. Jadeite, Nephrite, Turquoise, Serpentine Diffusion Beryllium Diffusion Beryllium diffusion introduces light elements during high-temperature heating to alter body color. It must be disclosed and usually reduces value compared with natural color. Sapphire and Ruby, especially orange, yellow,… Diffusion Surface Diffusion Surface diffusion adds coloring elements near the surface. It is less durable than body color because repolishing or recutting can remove the treated layer. Blue Sapphire and Star Sapphire Color Enhancement Dyeing, Pearls Dyeing changes pearl body color to imitate naturally colored pearls or create fashion colors. It must be disclosed. Freshwater Pearls, Akoya Pearls, cultured pearls Impregnation Polymer Impregnation, Jadeite Acid bleaching followed by polymer impregnation improves transparency and color appearance but greatly reduces value. Jadeite, especially B jade and B+C… Clarity Enhancement Resin Filling, Emerald Resin filling is a clarity enhancement similar in purpose to oil but often more stable. It must be disclosed and graded by extent. Emerald Color Enhancement Sugar-Acid Treatment Sugar-acid treatment darkens porous material by carbonizing sugar inside the structure. It is deceptive if sold as natural color. Turquoise and porous blue-green ornamental materials Clarity Enhancement Fracture Filling, Diamond Fracture filling improves apparent clarity but is not permanent under heat, repair, or harsh cleaning. It must be disclosed. Diamond Color Enhancement HPHT Color Treatment High pressure high temperature treatment can remove brown color or create fancy colors in suitable diamonds. Lab testing is often required. Diamond Color Enhancement Irradiation, Diamond Irradiation changes diamond color by creating color centers, often followed by annealing. Disclosure is required. Diamond Color Enhancement Irradiation, Tourmaline Irradiation can alter tourmaline color centers. It may be used alone or followed by heating. Pink, red, green, blue and multicolor… Clarity Enhancement Laser Drilling Laser drilling removes or lightens dark inclusions to improve clarity appearance. It is stable but must be disclosed. Diamond Composite Filling Lead Glass Filling Lead glass filling turns very fractured ruby into a composite material. It is far less durable and far less valuable than untreated or simply… Ruby, low-grade Corundum