2006-12-30 19:57:25 · 9 answers · asked by joe o 1 in Business & Finance ➔ Other - Business & Finance
No one can just look at (or bite) a piece and tell you for certain whether it is gold or not; a test will have to be done to determine it.
To be scientfically accurate a sample of the metal in question must be assayed in a testing laboratory, but the following two tests have been used for many years and often are sufficiently accurate for a craftsperson or the owner of the metal in question.
To answer "Is It Gold?":
With a small file, make a scratch in an inconspicuous spot. While wearing rubber gloves, use a wooden, glass or plastic stick to apply a drop of nitric acid to the filed spot. Observe the reaction. When done, rinse everything well in running water.
If there is no reaction, it's gold.
If there's a bright green reaction, it's base metal.
If there's green in the scratch, it's a gold layer over base metal (goldplate).
If there's a milky reaction in the scratch, it's a gold layer over silver.
To answer "What Karat Is It?"
Determining karat requires a testing kit containing nitric acid, aqua regia, samples of known karat, and a touchstone of slate or ceramic.
The gold object to be tested is rubbed on the stone ("touched") to leave a streak. A parallel line is made with one of the test pieces of known karat. Both marks are flooded with acid and the reaction are observed. When the sample colors at the same rate as the test streak, a match has been made. Nitric acid is used for low karat golds; aqua regia is needed for higher karats.
Please note: these tests are for your information only. They are not accurate enough to rely upon when representing a piece for sale.
Testing kits are available from most jewelry-supply houses. Please see the link at the end of this answer to go to Otto Frei--a very reputable and well-established to-the-trade supplier who will also sell many things to the general public. Most jewelers have testing kits to use when determining if something is gold or not and its approximate karat. It is probably easiest to take the item to a jeweler than to purchase and learn to use the testing kits yourself.
2007-01-01 18:26:46 · answer #1 · answered by shabocon 4 · 0⤊ 0⤋
The purity of gold is usually determined by a method called "Fire Assay", Basically the gold (and its alloying or impurity) metals are alloyed with lead a high temperature (1100 degrees Celsius) The molten lead oxidises to form litharge and this along with the base metals like copper and zinc are absorbed in to a porous ceramic cup called a cupel. By a quirk of nature the molten precious metals have a higher surface tension and are not absorbed into the cupel, where they remain as a molten bead. On cooling this bead is taken from the couple and rolled out very thinly, this is then usually coiled and dropped into hot dilute nitric acid which removes the silver. The gold that remains (as long as no platinum group metals are present) is the annealed at about 800 degrees Celsius which consolidates it and it shrinks in size to form a coil called a cornet. By knowing the start weight of the impure gold and the weight of the pure gold cornet the purity of the gold can be calculated. The result in normally expresses in carats, where 24 carats is pure gold, therefore 18 carat gold contains 18/24ths or 75.00 % by weight. For very high purity gold the impurities are measured and the gold is determined by difference.
2016-05-22 23:12:39 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Just bite the piece of gold. Isn't that what they do on TV and in the movies?
Oops, I just answered a question with a question, didn't I??
2006-12-30 20:04:02 · answer #3 · answered by curious ma 3 · 0⤊ 0⤋
Gold (if you have low iron) when rubbed on the skin of your face will leave a black mark. That is the easiest.
2006-12-30 20:05:44 · answer #4 · answered by miss bean 3 · 0⤊ 0⤋
Real gold is very soft. You should almost be able to bend it with your fingers.
2006-12-30 19:58:31 · answer #5 · answered by alwaysmoose 7 · 0⤊ 0⤋
Drop it on cement and if it "pings" it's not real. Real gold when dropped on cement falls silent.
2006-12-30 20:09:00 · answer #6 · answered by JFAD 5 · 0⤊ 0⤋
If you smash it with a hammer, it should smush with no trouble. and believe me, smushed gold is not less valuable, so don't worry about trying it.
2006-12-30 19:59:48 · answer #7 · answered by Anonymous · 0⤊ 0⤋
If you can dent it by biting it. It is Gold
2006-12-30 20:03:08 · answer #8 · answered by Anonymous · 0⤊ 0⤋
take geology 101 lab offered at your local college campus.
2006-12-30 20:08:31 · answer #9 · answered by Mk II 3 · 0⤊ 0⤋