No need to wait till next week...my Buddhist goldsmith did not close for Good Friday hol
I described what I wanted to do, and on the second explanation, he understood and suggested I let him do it for a small fee. He has some scrap 24k gold and his scales are accurate to 3 decimal places (way better than my 1 decimal place place el cheapo pocket scale).
4 grams of 24k and 1 gram of my unknown sample went into his crucible. He tilted the crucible back and forth while holding it in tongs and poked the molten metal with a graphite stick (which I don't have) to mix thoroughly. After the button cooled, he tested it and said it was now 20k. I asked permission to take photos, but was politely denied...security purposes I guess. At least he let me watch.
I hope my math is right...if not, please correct me!5 grams of 20k Au contains (5*20/24) grams of Au...that works out to 4.15 grams of pure Au content.
Now to find the karat of the sample which caused the dilution of the 4 grams of 24k and 1 gram of sample to become 20k...let X denote the karat of the unknown sample.
4.15 = (24/24)*4 + (X/24)*1
4.15*24 = 24*4 + X
99.60 = 96 + X
3.6 = X
If my calculations did not go awry, that means the sample is in the ballpark figure of 3.6k purity (with heavy emphasis on "ballpark"). As this stuff is natural, I will expect variations from lump to lump, but at least now I know what they roughly contain. That's another nagging monkey off my back!
I asked him to sell me a wee bottle of the formulation which he tested for 20k Au (the acids in my test kit jump from 18k to 22k), but he's not allowed to. Thanks again to GD for this methodology!
Posted on: March 29, 2013, 05:05:46 AM
Addendum: I didn't have to purchase the 4 grams of scrap gold. Canny goldsmith kept the button, my sample (which was about 3 grams before he chopped off 1 gram for the test) and he earned the testing fee of slightly under USD10. I think it's fair, considering he has to purify out his 4 grams of 24k from the button.
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