In Sri Lanka gem chrysoberyl is mostly found as water worn pebbles in the alluvial gem gravels. Chrysoberyl occurs only in a few colours and the common colours being yellow, golden yellow, brownish yellow, yellowish green, bluish green and faint olive green. Chrysoberyl occurs in varying degrees of transparency ranging from transparent and clear to cloudy translucent and opaque. The gemstones of this group are known to have wide distribution in and among the main gem producing regions of this country and are mostly lacalized around Rakwana, Bulutota, Deniyaya, Morawaka, Elahera, Avissawella, Pelawatte, Horana, Matugama, Panadura, Rathnapura, Aluthgama, Ambalantota, Agalawaththa, Bulathsinghala, Kalapugama and Mestiya.
Basic scientific details of Chrysoberyl family are mentioned below.

• Chemical Composition - BeO.Al2O3
• Crystal System - Orthorhombic
• Hardness – 8.5
• Specific Gravity – 3.72
• Refractive Index – 1.746 – 1.755

Some inclusions make stones cloudy, reduce transparency and produce reflection effects. These if properly oriented would, when cut ‘cabochon’ displays the cat’s eye effect. What is produced is a silvery streak of light which is displayed across the cabochon surface.