is one of the most precious metals in the world. It is present in
the rivers, seas, and the earthís crust and trace amounts are present
in plants and animals. It is, however, difficult and expensive to
extract. In modern mining operations approximately 3 tons of ore
are needed to extract one ounce of gold. The many desirable qualities
found in gold, along with its scarcity, have made it the most popular
metal for use in jewelry today.
in its pure state:
a melting point of 1945 degrees Farenheit (1063 degrees Celsius).
When alloyed (chemically combined) with other base metals the
melting temperature of the resulting alloy is changed. 18K yellow
gold has a melting point of 1675 degrees Farenheit and 14K yellow
gold has a melting point of about 1550 degrees Farenheit.
a specific gravity of 19.33. It is relatively heavy compared to
most metals, such as silver (SG 10.7) or iron (SG 7.8). A notable
exception is platinum (SG 21.4).
more malleable than any other metal and can be hammered into foil
so thin that it is almost transparent.
a unique ductility property allowing it to be drawn into wire
so fine it can barely be seen.
deep yellow in color. Its great reflectivity properties help keep
its brightness and color from fading with time.
not rust, tarnish or corrode. Gold jewelry recovered from ancient
Egyptian tombs is in the same state as when placed there over
4000 years ago.
softer than most other metals. On the Mohs scale of hardness (which
is a measure of a gemstone or mineralís resistance to scratching),
gold has a hardness value of 2 to 2.5. Diamond has a value of
10. Pure gold may easily be scratched. Fortunately, gold becomes
harder when alloyed with other base metals.
relatively scarce and therefore expensive. It is estimated that
only 125,000 tons of gold have been mined the world over since
the beginning of time.
able to bond with other base metals. This property gives rise
to the many different colors available in modern gold alloys.
ancient times the purity of gold has been defined by the term karat,
which is 1/24 part of pure gold by weight. Pure gold is equivalent
to 24K. Gold purity may also be described by its fineness, which
is the amount of pure gold in parts per 1000. For example, a gold
ring containing 583 fine gold has 583 parts (58.3%) gold and 417
parts (41.7%) of other base metals.
Trade Commission rules require that all jewelry items sold in the
United States as gold shall be described by "a correct designation
of the karat fineness of the alloy." No jewelry item less than 10K
may be sold in the United States as gold jewelry.
following table lists the relationship between different international
of Gold Karats
weight of a piece of gold jewelry is a factor that helps to determine
its value. It is important because it is an indication of the amount
of fine gold in an item of jewelry. Grams (g) and pennyweights (dwt)
are the units of weight most commonly used in weighing gold. Gold
and silver are almost always weighted in the troy system of weights
where one pound troy equals twelve troy ounces and twenty pennyweights
equals one troy ounce. The Avoirdupois weight system, where one
pound equals 16 ounces, is used in the United States for most everything
except precious metals. The following table summarizes useful weight
0.643 dwt = 0.0032 oz t = 0.035 oz av
1.555 g = 0.05 oz t = 0.055 oz av
troy ounce (oz t)
31.103 g = 20 dwt = 1.097 oz av
ounce avoirdupois (oz av)
28.3495 g = 18.229 dwt = 0.911 oz t