CL of Cut Stone Cabochons

CL of two nearly opaque colorless cabochons: The red CL belongs to a 2.53 ct Geuda sapphire from Sri Lanka prior to its heat treatment, when its daylight color turns into a fine blue. The nearly egg-yolk CL color has to be attributed to manganese activator ions in a rare apatite cat's eye from the Austrian Alps (Museum for Natural History Vienna, No. M3894). Cond.excit.: 12 kV; 0.9 mA. Dr. Johann Ponahlo, Vienna.

For a larger view, click on the corresponding photo.