Gold Measurements

Gold measurements can be a bit confusing. The weight of gold is measured in troy ounces (1 troy ounce = 31.1034768 grams), but its purity, or "fineness" has been measured in a few different ways: "parts fine," "% gold", and karats. (A major point of confusion is between "carat," which is a measure of weight for precious stones, and "karat", which is a purity measure for gold. The terms are used distinctly, even if they have the same derivation.) According to at least one source, the terms karat and carat derive from Arabic and Greek words meaning "the fruit of the carob tree." Apparently, the seeds of the fruit, remarkable for their consistency, were used to balance the scales used by merchants at ancient bazaars[1]. Karats now refer to the ratio of gold found in a sample. There are 24 karats, so pure gold is 24 karats. The percentage of gold in a piece is therefore the number of karats/24. Thus 96.5% gold is 23 karat (23.16 to be exact).

The legally permissible "karatage" for an item to be called gold historically has differed from country to country. In the U.S. 10 k is the legal minimum accepted standard of gold karatage, with 14k the most popular. In France, Italy and Switzerland, 18k is the lowest permissible standard to be called gold. England accepts 9k gold, while in some countries of the world, 8k is the legal minimum standard.

24 K = 100% Pure (European Marking Fineness 999)
18 K = 75% Pure (European Marking Fineness 750)
14 K = 58% Pure (European Marking Fineness 585)
10 K = 42% Pure (European Marking Fineness 420)

It should be noted that gold is rarely as pure as advertised. 14k karat averages at about 55% purity rather than 58%.

Abbreviations

K, k, KT, Kt, kt, CT, ct are all abbreviations used for karat or carat

KP, kp Karat Plumb, Plumb is used to guarantee gold content is not less than shown.

GP, gp, G.P. Gold Plated- refers to a metal item that has a very thin layer of gold applied to it. The thin layer normally wears away more quickly than gold in a gold filled item. It has a very thin layer of gold bonded to a base metal core. The layer of gold in gold-plating is only required to be seven-millionths of an inch thick.

GF, gf, G.F. Gold Filled- refers to a metal item that has a thin sheet of gold applied to a base metal core but the layer is thicker than in plated items. The layer of gold in gold-filled items is about one hundred times thicker than gold-plated items. Newer items contain markings that indicate how much and what type of gold was used in the layer. A marking of 1/20 12K G.F. means that the piece is at least 1/20th 12K gold by weight. In gold-filled products, the gold layer must be at least 1/20th (5%) of the overall product, by weight. Any purity of gold may be used; most gold-filled products are made with 12k or 14k gold. The purity of gold used can be determined by the notation in front of the words gold-filled. 14/20 Gold-filled and 14k Gold-filled both refer to a gold-filled product in which 14k gold has been bonded to the base metal core. Likewise, 12/20 Gold-filled and 12k Gold-filled indicate that 12k gold has been bonded to metal.

HGE, H.G.E., hge Heavy Gold Electroplate, is also sometimes called Vermeil. Vermeil consists of a base of sterling silver coated or plated on all significant surfaces with gold, or gold alloy of not less than 10 karat fineness, that is of substantial thickness7 and a minimum thickness throughout equivalent to two and one half (2 1/2) microns (or approximately 100/1,000,000ths of an inch) of fine gold.

Notes

1. The trouble is, that turns out not to be true, as Lindsay Turnbull from the University of Zurich, Switzerland, and colleagues found out. The team collected and weighed 550 seeds from 28 carob trees in Mallorca and found they are just as variable in weight as seeds from 63 other species of tree (Biology Letters, DOI: 10.1098/rsbl.2006.0476).So how did carobs come to be regarded as constant in weight? Turnbull speculates that people just selected the seeds they wanted to use. To test the idea, she set up a perception experiment. "People were able to identify the heaviest seed of a pair even when the difference in weight was very small, 1/100 of a gram."

Weight Systems

1 troy ounce = 480 grains
1 grain = 64.798 91 milligram
1 troy ounce = 31.1034768 grams
24 grains = 1 pennyweight
20 pennyweight = 1 troy oz
12 troy oz = 1 troy lb

1 Troy Ounce = 31.103 Grams
1 Pennyweight =1.555 Grams
15.432 Grains =1 Gram
1 Grain = .0648 Grams

Be sure you know the difference between grams and grains! Some unscrupulous sellers will intentionally mislead the public by listing weights with incorrect abbreviations ("g" is for grams and "gr" is for grains).

    Gm = Grams

    Oz = Ounce

    ozt = Troy Ounces

    dwt = Pennyweight

    Kgm = Kilogram (1000 grams)

One way to do conversions is using the google calculator

These sample queries show how easy it is:

	12 pennyweight in ounces
	1 troy ounce in ounces