IGI Certified Hackmanite ( Sodalite ) . Its quite rare to find gem grade hackmanite. It has strong fluorescence & unusual gem because it exhibits a special optical property know as tenebrescence,” a type of reversible photochromism . This feature allows gems to temporarily change color when exposed to different light form . It has silk form inclusion as visible as in the photos. Color change effects can be spotted it depends on the light. It has very good size & good luster. Production of Hackmanite is very limited. Collectors item IGI Report No : 706541894 Weight : 24.88 ctw Color : Purple Cut : Cushion Mixed Cut Transparency : Transparent Measurements : 18.18 x 16.38 x 13.20mm Characteristic : Natural inclusions pattern Comment : Tenebrescence Effect No indication of thermal treatment Origin : Badakshan Afghanistan / Not mentioned in report Shipping will be via FedEx with full insurance