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Old 06-21-2012, 09:26 AM
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KingTotsalot KingTotsalot is offline
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Join Date: Mar 2011
Location: Mabelvale, south of Little Rock, Arkansas
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Originally Posted by Metal-Magnet View post
I've saw on pawn stars them scratching gold on some kind of pad and putting some type of liquid on it. Anyone know of this method?
This is a long time common method for testing gold. But it comes with some caveats.

First you need the right tools and right acid. You can buy the tools and acid but with the price of gold way up, the price of the set would be very expensive now.

The set consists of a black very fine grained stone, like black Arkansas Novaculite, available through some Arkansas oilstone dealers...listed as Black Arkansas as the trade name. You want the opaque stone not the translucent.
Then you need a set of gold grading needles....the needles are 8, 10, 12, 14, 16, 18, 20, 22 Kt. Should be available through a Jeweler's Wholesale House or through select retailers to the jewelry trades...Check out a Jewelry Trade show to find these equipment sellers.

The object to be tested is rubbed against the black stone, "Touchstone" as it is known in the jewelry trades, to obtain a metallic streak. Then if the piece is marked, the appropriate needle is rubbed on the stone next to the 1st streak. Finally a drop of nitric acid is applied to both streaks. The acid eats the alloys away in short order, and what remains is gold.

A hand lens is then used, usually 10 X, to compare the color and distribution of the gold remaining with standard needle streak.

This test is somewhat objective but does prove that gold is present. Most jewelry stores and pawn shops that test this way, then give an offer based on a percentage of the total gold weight at 2Kt less than the supposed value. Experience has shown, particularly with unmarked jewelry, that this test may over estimate the gold content more often than underestimate it, and by doing so, the store owner is protecting his bottom line, which is the melt value of the gold should he send it in for scrap.

Hope you find this info of some interest. PS: The King does know his Gold!

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