Chalcedony is the form of Quartz that is compact and microcrystalline. It occurs in many different forms, colours, and patterns, and many varieties have been used as gemstones since antiquity. In the gemstone trade, the term Chalcedony is often used specifically to describe the white, grey, or blue translucent type of Chalcedony, but its technical term includes all additional varieties.

Stock Sizes:Available in round and oval cabochon
Round: 4mm – 10mm
Oval: 6x4mm – 25x18mm

Chemical Formula: SiO2
Crystal Structure: Hexagonal
Colour: White, Blue, Red, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Black, Banded, Multicoloured
Hardness: 6.5 – 7 on Moh`s scale
Refractive Index: 1.54 – 1.55
Specific Gravity: 2.63 – 2.65
Cleavage: None

Treatments: Dying Chalcedony, Agate and Onyx first involves boiling the stone in a strong bicarbonate solution, then soaking the stone in a chemical solution.

Red: iron nitrate solution
Green: chromic acid or nickel nitrate
Brown: sugar solution followed by heat.
Blue: red or yellow prussiate of potassium followed by soaking in iron sulphate solution
Black: sugar solution followed by sulphuric acid.

Care: Most cleaning methods including ultrasonic and steam cleaners are safe but we suggest cleaning your gemstones with warm soapy water whenever possible. Chalcedony is affected by some acids, and heat may change the colour. Chalcedony is quite porous, which means that it can be easily stained and absorbs chemicals and colours very easily.