Work out gemstone weight instantly with clear inputs, formula shown and shareable results.
The trade estimate multiplies length by width by depth by specific gravity by a shape factor, which is about 0.0061 for a standard oval or round brilliant. Shape factor matters because the same bounding box holds very different amounts of material in an emerald cut versus a brilliant, so the factor changes by cut.
Weight estimate
carats = length x width x depth x specific gravity x shape factor
carats = length x width x depth x specific gravity x shape factor. The trade estimate multiplies length by width by depth by specific gravity by a shape factor, which is about 0.0061 for a standard oval or round brilliant.
Shape factor matters because the same bounding box holds very different amounts of material in an emerald cut versus a brilliant, so the factor changes by cut.
Enter length, width, depth, specific gravity. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.