Weights and Measures
The purpose of this article is to
acquaint you with some of the terms used in weighing,
measuring and calculating
quantities of gold. It is useful if you are interested in
understanding more about what is involved in the buying and
selling of gold.
You can use this
better understand the
relationship between weight, fineness (or purity) and content of
gold coins and other gold objects.
Let's get started...
When selling your gold coins,
jewelry or "scrap" gold -
when a dealer quotes you a price for your gold by pennyweight or
gram, this information can help you calculate what discount s/he
is offering in relation to the spot price of gold.
(and impress!) your friends and family members -
who want to buy gold or are interested in selling their gold
coins or jewelry and don't have the slightest idea of what it is
worth or how to proceed.
The Troy Weight System
The Troy weight system is the
universal system used to weigh gold (and silver). Unlike the
Avoirdupois weight system, the system commonly used in the United
States that is based on 16 ounces to the pound, the Troy weight
system is a series of units of weight based on a pound of 12
ounces and an ounce of 20 pennyweights or 480 grains.
Under the Troy system...
grain (the smallest unit) = 0.042 pennyweight; metric equiv. =
To see how this weight system is used
as it relates to gold, lets look at two popular gold coins - the Gold
American Eagle and the gold Canadian Maple Leaf.
Each contain one Troy ounce of fine gold. The Maple Leaf has a
gold fineness or purity of .9999. Since this coin is pure gold,
its gross weight and net gold weight are both one Troy ounce or
The Gold American Eagle is not pure
gold. It is alloyed for hardness and has a gold fineness of .9167.
In order for this coin to contain one Troy ounce of gold, the
gross weight has been increased to 1.0917 Troy ounces or 33.956
1 pennyweight = 24 grains = 0.05 ounces; metric equiv. = 1.555
1 ounce = 20 pennyweight = 480 grains; metric equiv. = 31.103
1 pound = 12 ounces = 240 pennyweight; metric equiv. = 0.373
The Avoirdupois Weight System
Under the Avoirdupois system...
grain (the smallest unit) = 0.036 drams; metric equiv. =
1 dram = 27.343 grains = 0.0625 ounces; metric equiv. =
1 ounce = 16 drams = 437.5 grains; metric equiv. = 28.349
1 pound = 16 ounces = 7,000 grains; metric equiv. = 0.453
can convert Avoirdupois to Troy ounces by multiplying
Avoirdupois oz. times 0.911
can convert Troy ounces to Avoirdupois ounces by
multiplying Troy oz. times 1.097
The Gold Karatage System
Most gold jewelry uses the
Karatage system to define the gold content in the piece.
It is used to to identify the fineness or purity of gold
as a fraction of 24 parts. Pure gold (or fine gold) is 24
karats which has a fineness of .9999 or 99.99%. Sometimes
gold content is expressed in parts per thousand so if you
see 500 stamped on your gold jewelry, it is an alloy
containing 50% gold.
You can use the following
Karatage list as a guide to for determining gold fineness
and percentages in the U.S.
24 karats = .9999 fineness = 99.99% gold purity
22 karats = .9167 fineness = 91.67% gold purity
18 karats = .7500 fineness = 75.00% gold purity
14 karats = .5833 fineness = 58.30% gold purity
12 karats = .5000 fineness = 50.00% gold purity
10 karats = .4166 fineness = 41.66% gold purity
Let's say you have a piece of
gold jewelry you are interested in selling. You see a 18K
stamp on the jewelry so you know it is 75% pure gold.
Since gold is such a soft metal, the remaining 25% is
likely one or more metals to "harden" the piece of
jewelry, add color to it or both.
Most dealers will quote you a
price for your gold by gram or pennyweight, taking into
account the gold fineness. So, in the example above, they
will give you a price of what they are paying for an 18K
piece of jewelry based on the weight and a gold fineness
of .7500 or 75% purity.
The question then becomes "Is
that a fair deal? What percent discount is their offer in
relation to the spot price of gold?" That is the subject
of a another article - Selling
Your Scrap Gold.
I have made every
reasonable effort to produce an informative and helpful article on
Gold Weights and Measures based on my research and experiences.
However, I make no representation or warranties of any kind with
regard to its completeness, accuracy or suitability for any specific
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Investing Simplified - Gold Weights and Measures