Specific Gravity Calculator for Gemstones
A gemologist friend of mine recently complained about the tedium of calculating gemstone and mineral specimen specific gravity via the hydrostatic weighing method. You see, after weighing the specimen in air (at room temperature) and in water (at 4º Celsius, ideally) one must do a little math to determine the specific gravity (S.G.) of a sample. The formula is very simple: It’s the weight in air, divided by the loss of weight in water (at 4º Celsius). Or: the weight in air, divided by the weight in air minus the weight in water. Simple. Right? But when you do dozens (or more) of these a day, it gets tedious. High-end lab equipment will do the calculations for the technician, but my friend doesn’t have such equipment. And such equipment doesn’t help if one is in the field.
There are a few calculators on the Web, but most are not mobile-phone-friendly, and he likes to use his iPhone around his lab. So I coded this simple little web app to help my friend in his time of need. Of course he wants a native iOS app, but that seems a bit overkill for such a simple task.
Now I just need to update this site to modernize it and make it mobile-friendly. So little time…
If you’d like to use the calculator, you can go here and calculate ‘til your heart’s content. It’s labeled to suggest entering carat weight (for precision), but entering weight in grams is fine as well (but rounding may negatively affect accuracy, depending upon your precision). Most important is to not mix units of measure.