The rough was sourced in Tanzania & cut by Alan Poultney in 1980
 
The tanzanite (Zoisite):
 
Invent No: APD175
 
Estimated weights colours & clarities
Estimated weight: 3.17cts
Cut: fancy modified step cut
Estimated Colour: transparent purple/blue
Colour  Distribution: even
Hue: intense
Tone: very strong
Estimated Clarity: EC (Eye Clean)
Brilliance: 90%
Girdle: polished
Dimensions: 9.86mm x 7.98mm x 5.39mm    
                           (Length x Width x Depth)
Refractive Indices: 1.691 
Specific Gravity: 3.35
Hardness: 6  -  6.5
Orign: Tanzania Africa
Treatment: No eveidence of heat treatment - the stone was cut down the "C" axis.