Taking the valuation process used by the Gemwold Guide as an example, I’ll outline how it works for tsavorite. The Guide would deduct a half a grade to one whole grade for the loss of brilliance which windowing causes. You would go from 70 to 100% brilliance with no window to a half grade less with a window that gave 60 to 70% brilliance or one grade less with a window that gave 40 to 55% brilliance. Since a window usually involves the area of the whole table, which is 50 to 60% of the stone’s area, it would be easy to go from 95% brilliance to 50%. Then you have to consider that the stone’s color is washed out by a window, so the color grade is affected, too. As an example, in a 3 to 5 ct stone, if you went from grade 8 to grade 6.5, your valuation would change from about $2,500/ct to about $2000/ct. Some criticise the Gemwold Guide for being too high, but I think the price difference would still be about the same, so about $500/ct…for a 3 ct stone, this is about $1500. Against this balance the loss of weight of about 10 to 15% to recut to no window. So loss of weight about $500 to $700, but gain in valuation, about $500/ct…$1500-$600= +$900. At the lower grades, the difference between grades could be just $200/ct or less and at the highest grades as much as $1800/ct. So for fine tsavorite, it would probably pay to have it recut. If I were to recut such a stone, I would use an apex crown if the stone were very shallow, so I wouldn’t lose too much weight. Recutting a stone might cost $100 to $300, so the net effect is still positive. I hope this info is helpful. -royjohn
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