Down and dirty Specific Gravity

fdutra said:

"Green gold: Unless one is familiar with the appearance of green gold, the term can be quite misleading. The green color, like rose gold, is very subtle. Green gold is best described as yellow gold with a slightly greenish hint (not a definite green like this background). Green gold is most noticeable when it is used in a piece of jewelry next to areas of yellow, white, and pink gold. The classic mixture that produces green gold is an alloy of pure yellow gold and pure silver -- though, for rings, harder metals such as nickel or zinc are sometimes added to make the gold more durable. 14K green gold would contain fourteen parts yellow gold and ten parts silver. 18K green gold would contain eighteen parts yellow gold and six parts silver.

Whitfield Jack"

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Kapidr said:

Itsaring and I tried this this morning and we kept coming up with .99. Then we rechecked your notes and it says divide step 2 by step 3 but actually I think you meant divide step 1 by step 3. Once we divided step 1 by step 3 the numbers came out right. VERY COOL!

You said you could tell the karat weight with more math. Could you also tell if a stone is a true Tsavorite with this method. I believe I have a ring with a 2.96 karat Tsavorite and if I'm correct that could make it a 10,000 to 15,000 dollar stone as Tsavorite is rare over 2 karats.

Would you share how to tell total Karat weight of diamonds in a ring as well as if it's possible to determine if a gemstone is real?

Thanks!

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fdutra said:

Thanks for pointing out that error,,, must have been very frustrating, sorry. I've corrected the original post.

The SGs of many gemstones are very close, usually making definitive identification difficult using this primitive method, although you should be able to say it "could be" or it "can't be" once you have figured out it's SG. For diamonds you can rule out cubic zirconium, but moissanite is a lot harder since it only differs from diamond by .3 SG units. it can be done but you have to be real careful and know the exact composition of the ring's metal (like 14k white gold), and calculate the volume of the stone before plugging it into the modified alloy equations (Hauser & Miller) I pmed you with some "not ready for prime time" notes and equations,,, see what you think.

You may be able to positively id the Tsavorite by a process of elimination similar to what pro gemoologists do.
Example: If the SG is right for Tsavorite, and and all other red gems have a different SG, you have Tsavorite!

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Numil said:

Thanks for re-posting this. Its great info. I have a ring I'll be trying this on later today. I'll keep you posted as to how it goes but should be easy as cake.

Update:

Ran the specific gravity (SG) test as advertised under this thread and came up with a 8.0 to 9.5 SG for the ring in question. Working with small amounts and my scale which measures in tenths of a gram may not be sensitive enough.

While the ring shows up on my ATPro VDI as 42-44 smack dab in the gold zone I produced a graph on the SG information on different gold alloys and then added a trend line it suggests that the ring may be 8K or less..I still have doubts.

I'm not done so when I return to the university (more sensitive and exact measuring devices) I can run some more tests o n specific gravity and acid testing and narrow down the metal/alloy of this ring. Still, its been said that a junker find is better than more clad. I whole heartedly agree.

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