ONYX Green for Budha / Red for Mangal & Surya / Black for Sani & Rahu.

• Gem-Group : Chalcedony.
• Crystal Structure : Trigonal.
• Composition : Silicon Dioxide , SiO2.
• Hardness : 7
• Availability : World wide.
• Specific Gravity : 2.61
• Refractive Index : 1.53-1.54
• Double Refraction :  0.004
• Lustre : Vitreous
• Metal : Silver.
• Process : Process followed as that of the planet for which it is used.