Bleaching
- Nature of gemstone: Stones such as Ivory, Pearl, Tiger's Eye, Coral, Jade.
- Materials used: Hydrogen peroxide or any other bleaching agent.
- Possible effects: Generally used to remove colour discrepancies and provide a uniform coloration. In the case of Tiger's eye the dark brown shade is bleached to a pleasing yellow.
- Identification: This is generally not easy to detect.
Organic Gemstones
Inorganic Gemstones
- Andalusite
- Apatite
- Azurite
- Benitoite
- Beryl
- Calcite
- Chalcedony
- Chrysoberyl
- Chrysocolla
- Corundum
- Cuprite
- C.Z.
- Danburite
- Diamond
- Diopside
- Dioptase
- Dumortierite
- Ekanite
- Enstatite
- Epidote
- Feldspar
- Fluorite
- Fuchsite
- G.G.G.
- Garnet
- Hematite
- Idocrase
- Iolite
- Jade
- Kornerupine
- Kyanite
- Lapis Lazuli
- Malachite
- Natural Glass
- Opal
- Peridot
- Prehnite
- Pyrite
- Quartz
- Rhodochrosite
- Rhodonite
- Sapphirine
- Scapolite
- Serpentine
- Sillimanite
- Sinhalite
- Sodalite
- Sphene
- Spinel
- Spodumene
- Strontium Titanate
- Sugilite
- Synthetic Moissanite
- Synthetic Rutile
- Taaffeite
- Topaz
- Tourmaline
- Turquoise
- Y.A.G.
- Zircon
- Zoisite