----International Gem Society (IGS) Article
What's the average gemstone faceting yield from a single piece of rough? Learn how to estimate how much material you'll need to cut to get the gem you want....
Read More in This Months Article: Anticipated Gemstone Rough Yield
When L. Allen Brown, owner of All That Glitters, is seeking rough, for a clean piece or a piece that has some inclusions that can be removed during cutting, the estimate used is a 20% yield. If the rough has a shape which is not far off from the final shape that would be faceted from a particular design chosen, then the yield will be higher. (In the case of faceting Turkish Color Changing Diaspore, because the crystals are rather shallow due to the habit/growth of the crystals, as well as some inclusions and issues that must be cut/ground out, the yield is typically very low - being only about 8%.) When one purchases rough, you are paying 100% of the price for the rough, but the yield of the finished gemstone could be only say 8% or 20% - so one is grinding away 80% to 92% of ones original purchase! This also assumes that one facets using the proper angles for that particular gemstone species and one desires a brilliant nice looking gem - as if one is going for final weight, then the yield could be higher, but the gemstone would not be as attractive as a well cut gemstone. We seek to produce the best looking gem and sacrifice the weight, thus, the gemstone costs us more in the long run when faceted. There is one cutter that is known in California who gets up to 50% of a yield from the rough, but he also doesn't use the correct angles in the very culet/bottom of the gem and this produces a window and there is no brilliance in the very center - something that we go to lengths to avoid. He claims he customers like this design/style, similar to old fashioned diamond cuts before diamond cutting and brillance became an art and pretty much mandatory. He may obtain a better yield and his cost for the finished gemstone is lower, but the beauty/brilliance suffers and most likely his customers just don't understand cutting and can live with brilliance around the periphery of the gem and a dead center...these gemstones should be at a lower price because of the better yield and also discounted because of the lack of beauty and brillance when compared to a gemstone that is properly faceted and has life! In most cases, a lower price on something is not better...
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