ON HOLD John O Natural Untreated Violet Blue Tanzanite Gemstone 5.31 CaratsPrice includes setting in 18k yellow gold, size 4 1 2, style 71627, as per our emails. One 5. 31 carat emerald cut tanzanite, Natural untreated violet blue exceptional (35% 65%) more blue color, VS1 clarity, cut grade excellent, measuring 8. 1 mm wide, 9. 6 mm long, 7. 6 mm deep. The proportions of the tanzanite are as follows: total depth 93. 8%, table width 48. 1%. The overall quality rating of this tanzanite is 983 out of 1000.