| Gold
ACID
TESTS:
Standard
acid tests for gold are based on the fact that gold will not
react to pure nitric acid, but it will react to a mixture
of 1 part nitric acid and 3 parts hydrochloric acid (a solution
called aqua regia). Copper, brass, and nickel turn green and
start foaming or hissing when nitric acid is applied. Gold
is the only yellow metal that does not react to nitric acid.
If
gold is lOK or less, it will probably show a reaction due
to the higher percentage of other metals. Aqua regia (the
nitric and hydrochloric acid mixture) can also be used to
estimate the gold purity because the speed at which it dissolves
gold is related to the percentage of gold present. For example,
14K gold is dissolved faster than 18K gold.
To
determine if a piece of jewelry is 14K or 18K, rub it on a
black stone slab such as slate or basalt to form a streak.
Then make streaks with pieces of known 14K and 18K gold on
the same slab. Apply a drop of aqua regia to each of the streaks.
Compare the time it takes for the gold to disappear. If the
unknown streak disappears faster than the 14K or 18K streaks,
it might be 10K. If it disappears at the same rate as the
14K streak it probably is 14K. If it disappears at the same
rate as the l8K streak, the tests suggests 18K gold.
Gold
testing acid kits with written instructions can be purchased
at jewelry supply stores. If you decide to buy one, have the
salesperson demonstrate how to use it. Pay close attention
to the safety precautions and never store or use the kit near
children because the acids are very caustic.
Pure
nitric acid is so dangerous that most jewelry supply stores
refuse to include it with their testing kits. It is advisable
for people unaccustomed to handling acids to have theirjeweler
perform these tests when they want to check their gold jewelry.
PRICE TESTS: If someone tries to sell you gold jewelry at
an unbelievably low price, be suspicious.
The jewelry may be gold plated, it may be of a lower fineness
or karat age than marked, or it Gold may be made of pieces
of gold soldered to another cheaper metal.
This
yellow color
The
thickness
percentage
of copper
If
you prefer to buy
Accidentally spotted
Apply
a drop of aqua
Determined
by calculating
Becoming increasingly popular
white
gold prongs
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