玉瓍 - 碧玉

Appearance:

• Chalcedony (kal-SED-uh-nee) is microcrystalline or cryptocrystalline quartz; hexagonal (trigonal) crystal system; chemical composition SiO2
• Natural material no any treatment
• Opaque
• Green to yellowish green with black, brown, grey stripes
• Jasper – general variety term applied to semi translucent to opaque chalcedony of any color or combination of colors, except solid black or specially labeled material, such as bloodstone, onyx, etc.

Identification:

• Refractive Index: 1.535-1.539; 1.53 or 1.54 spot reading
• Birefringence: usually not detectable, but may show .004
• Pleochroism: none
• Ultraviolet Fluorescence: generally inert (LW and SW); some may fluoresce a yellowish green (LW and SW)
• Specific Gravity: 2.60 (+.10,-.05)
• Polish Luster: greasy to vitreous
• Fracture: conchoidal; sometimes granular
• Luster: dull to waxy
• Cleavage: none
• Hardness: 6 ½  to 7
• Toughness: good

Birthstone Designation(s):

• Jasper – 10:00 pm

Sources:

• South Africa

Stone information is reference from:

• Gem Reference Guide, Published by GIA. ISBN 0-87311-019-6
• Gemstones of the World, Published by Sterling Publishing Co., Inc NY, ISBN 1-4027-4016-6
• Encyclopedia of GEMSTONE, Published by ISHINSHA CO., LTD. ISBN 978-986-251-831-1