When evaluating jewelry how does one determine the carat weight of a gemstone included in a particular piece without dismantling it gem by gem?

I have a simple tool that I use when Iâm in the field that has just about every stone shape and size that gives me the approximate carat weight of a stone. These tools are pretty accurate on modern cut stones. Other than that you would measure the stone and just do the simple math of the stones cut. It all depends on the cut of the stone. I donât have the variations on hand at this moment. They are easily found.

Otter

Hello IMDone,

If you know the identity of the gemstone and the type of cut, and if you can measure its dimensions, you can use some formulas to estimate its carat weight. Youâll need to look up the specific gravity of the gemstone.

Here is an article that explains the procedure.

Hope this helps,

Pedro

IGS Admin

So in short you can calculate the carat weight of an oval citrine by multiplying the volume times the SG times .002?

I donât think âdiameter x diameter x depth,â where the diameter is the average of the diagonal, length, and width, equals the volume of an oval âellipsoid.â (But Iâm not sure about that). Otherwise, the formula is diameter x diameter x depth x SG of citrine x .002.

See this is the sort of stuff they should be teaching in high school and how to do your taxes. Its absolutely pointless to calculate the speed and destination arrival times of trains when you consider that weâre at the mercy of the conductor and his own schedule which is more often than not a completely different schedule than the one suggested by the rail line. Jewels and taxes, thatâs where itâs at. Now where did I put that Geometry for Dummies book? Thanks for the input men. The formula works. Youâre an asset to the field, Much appreciated

Do you know of any phone apps that might help me in the field?

As far as phone appsâŚIâm tech lost! I do not believe there is one but if there is I would love to know also. I have been using my templates and doing the calculations and coming pretty close in the field. knowing the SG of your stones will be a great help in this. Zircon would be the on stone that can throw you off due to its popularity and SG.

All the best,

Otter

Otter, I did find this site that I can access on my phone when WiFi is available and curious to know what you think of it in terms of accuracy.

http://dendritics.com/carat-weight/

So as far as tech goesâŚ on my i phone i have the IGemology appâŚ which has a calculator in it that factors size and gravity of stone and gives you an estimate. its like 15 dollars to own however since you are in the gem industry its a tax write off for tax season. If your worried about the 15 bucks lol.

During these times $14.98 would have been okay but $15 seems way out of my league. LOL Thanks for the tip.

I wanted an easy solution to this and other problems, my hunt led me to âGemology Tools Professionalâ great program with a host of info and tools. Worth checking out and no I donât have anything to do with the company

Thanks for the tip! This is great stuff.