Cornelian (also spelled carnelian) is a brownish-red mineral which is commonly used as a semi-precious gemstone. Cornelian is a variety of the silica mineral chalcedony coloured by impurities of iron oxide. The colour can vary greatly, ranging from pale orange to an intense almost-black colouration. It is most commonly found in Brazil, India, Siberia, and Germany.
Stock Sizes: Available in cabochon and flat signet stones
Round Cabochon: 2mm – 25mm
Oval Cabochon: 5x3mm – 40x30mm
Pear Cabochon: 7x5mm – 30x22mm
Oval Signet: 6x4mm – 25×18
Cushion/Antique Signet: 6x4mm – 20x15mm
Free form cabochon and mixed slices/carvings are available
Chemical Formula: SiO2 silicon dioxide (Quartz variety)
Crystal Structure: Microcrystalline
Colour: Colour can vary greatly, ranging from pale orange to an intense almost-black colouration.
Hardness: 6.5-7 on Moh`s scale
Refractive Index: 1.530 – 1.540
Specific Gravity: 2.58–2.64
Treatments: Dying (Dying Chalcedony, Agate and Onyx first involves boiling the stone in a strong bicarbonate solution, then soaking the stone in a chemical solution.)
Care: Agate can be cleaned very easily using warm soapy water and a soft brush. Keeping in mind its hardness and durability, be sure to not use any other objects that are harder than agate for scrubbing or cleaning. Agate should avoid any prolonged exposure to extreme of heat as it may cause permanent damage to the gemstone.