Gold is one of the most precious metals in the world. It is present
in the rivers, seas, and the earths 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.
of Gold] [Fineness (Karat Value)]
[Gold Karat Information Chart]
[Weighing Precious Metals]
[Gram/Pennyweight/Ounce Weight Conversion
Gold in its pure state:
- Has a melting point of 1945 degrees Fahrenheit (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 Fahrenheit and 14K yellow gold has
a melting point of about 1550 degrees Fahrenheit.
- Has 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).
- Is more malleable than any other metal and can be hammered into
foil so thin that it is almost transparent.
- Has a unique ductility property allowing it to be drawn into wire
so fine it can barely be seen.
- Is deep yellow in color. Its great reflectivity properties help
keep its brightness and color from fading with time.
- Will 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.
- Is softer than most other metals. On the Mohs scale of hardness
(which is a measure of a gemstone or minerals 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.
- Is 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.
- Is able to bond with other base metals. This property gives rise
to the many different colors available in modern gold alloys.
Since 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.
Federal 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.
Karat Value Definitions:
- Karat System: A system of measurement based on 24 karats
being "fine" or "pure" gold. 1 karat equals 1/24th fine gold by
weight. This is the system used in the United States.
- Plumb Gold: Karat weights are usually determined with a
small, fractional variance allowed. Karat gold which has no variance
and is exactly the precise fractional karat weight is called "plumb"
- European System: A system of measurement based on a fraction
of 1,000; or the number of grams of gold in 1 kilogram of alloy.
The following table lists the relationship between different international
||Normal European Stamping
||9 in 24
||10 in 24
||12 in 24
||14 in 24
||583 or 585
||18 in 24
||22 in 24
||24 in 24
||999 or .99999
The 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
|1 gram (g)
||= 0.643 dwt = 0.0032
oz t = 0.035 oz av
|1 pennyweight (dwt)
||= 1.555 g = 0.05 oz
t = 0.055 oz av
|1 troy ounce (oz
||= 31.103 g = 20 dwt
= 1.097 oz av
|1 ounce avoirdupois
||= 28.3495 g = 18.229
dwt = 0.911 oz t