Gem Cut Yield Calculator

Cutting a rough gemstone always loses weight -- to sawing, to shaping a girdle and facets, and to cutting past visible inclusions -- and this calculator estimates how much Polished Weight to expect from a lookup table of typical recovery rates by Rough Shape and Target Cut, then subtracts an Inclusion Level penalty. An octahedral rough cut to an emerald cut recovers the most in this table, around 55%, because octahedron rough already has faces close to a finished stone's natural angles; a crystal fragment cut to a round brilliant recovers the least, around 22%, because irregular rough needs the most material removed to reach a symmetric shape. Inclusion Level then subtracts further: 0 points for clean rough, 3 for minor inclusions, 8 for moderate, and 15 for heavy inclusions that need cutting around, with the result floored at a 5% minimum yield so the estimate never goes to zero or negative.

Rough Weight then scales Polished Weight and Weight Loss proportionally at whatever yield percentage the shape/cut/inclusion combination lands on -- doubling Rough Weight doubles both outputs, but it does not change Yield or Loss Percent at all, since those are pure percentages driven only by shape, cut, and inclusions. What this doesn't capture: the actual cutter's judgment about where to saw, species-specific behavior like a diamond's cleavage planes or a sapphire's color zoning, and window/orientation decisions that a real lapidary makes stone-by-stone. Treat the result as a planning estimate for pricing rough, not a guarantee of what a specific stone will yield.