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. 10k is the legal minimum accepted standard of gold karatage, with 14k the most popular. 14k gold is also commonly found in cases where strength is important, like in earring backs and bracelet clasps. 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. 15k was the old Victorian standard, and dental gold is 16k.

Millesimal fineness

Fineness represents the purity of precious metals expressed in parts per thousand.

• 24 K = 99.9% Pure (European Marking Fineness 999)
• 22 K = 91.3%
• 18 K = 75% Pure (European Marking Fineness 750)
• 14 K = 58.5% Pure (European Marking Fineness 585)
• 10 K = 41.7% Pure (European Marking Fineness 420)

Some countries insist that there is no negative tolerance allowed (e.g. UK, where 18 carat is 750 fineness minimum) but in others a negative tolerance, typically 3 parts per thousand, is allowed (e.g. in USA, a fineness of 747 would be accepted as 18 carat). This causes difficulty in the mutual recognition of national marks/hallmarks , a problem raised in the European Union by the Houtwhipper ruling recently. Thus a piece of jewellery assaying at 747 fineness would pass in the USA as 18 carat but fail in the U.K.  14k averages at about 55% purity rather than 58% in the USA.

• .375 = 9K (England and Canada)
• .417 = 10K
• .500 = 12K
• .583 (.585) = 14K
• .625 = 15K
• .667 = 16K
• .750 = 18K
• .833 = 20K (Asia)
• .999 (1000) = 24K pure gold

Bars

The purity of gold bars (gold bullion) is usually expressed as a decimal figure ranging from ".0" (no gold) to .9999 (totally pure). London good delivery gold bars (weighing approximately 400 ounces each) must assay at least 99.5% pure gold; that is, 995 parts of gold per thousand parts of metal, or “995 fine“. Some gold coins and small gold ingots are made from gold that was refined up to 99.99% pure gold; that is, 999.9 parts per thousand, generally stated as .9999, or four nines.

What does 750 stamped on jewelry mean?

750 on a piece of jewelry signifies 18k ie 75% pure. It is common in Europe.

What does 585 or 583 stamped on jewelry mean?

585 or 583 on a piece of jewelry signifies 14k. Technically 14K should be 583 (14/24 = .583333) but most manufacturers have adopted the European way and make 14k gold a tiny bit over 14k, so the mark is 585 in most 14k jewelry.

What does “LU-RAY” mean?

 This signifies the jewelry is made from low grade Lurithium Rayon, a cheap substitute for gold.

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. Thus 14KP means that it is exactly 14K. Otherwise there may be some negative tolerance.

K.P. Karat plate

GP, gp, G.P. Gold Plated- refers to a metal item that has a very thin layer of 10k gold or better 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 ( also called Gold Overlay) - refers to a layer of at least 10-karat gold that has been permanently bonded by heat and pressure to one or more surfaces of the support metal, then rolled or drawn to a prescribed thickness. The karat gold must be at least 1/ 10 of the total weight. 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. The French term for this is doublé d'or.

GS Gold Shell

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.  

KW White gold

KY Yellow gold

MIL 1 thousandth of an inch. Refers to thickness of gold plating.

MILL 1 millionth of a troy ounce.

JSN, PR, HJ These are all maker or design marks and have no relevence to the value. HJ is short for Heriff Jones.

pall Palladium

plat. Platinum

RGP, RG stands for rolled gold plate or rolled gold. This means that it is gold filled.

WG White gold

YG Yellow gold

YLTM Yellow Lustrium. Lustrium is a mixture of nickel and chromium. Yellow lustrium is fused with an amount of real gold all the way through so even if scratched, there will not be a difference in color. The gold content is higher at the surface, and becomes less, deeper into the metal. The cost is lower than 10kt Gold.

316L - High-grade Stainless Steel

Aurum Utalium - pseudo-Latin term used by scammers. It is meant to mean 'useful gold'.

• sterling
• sterling silver
• ster
• 925, 92.5, .925
• AG925
• argent sterling
• 835 (.835) - a lower quality of British Sterling Silver
• 925 NV - Nevada Silver
• Taxco
• .999 Fine - Pure Silver

Guide to Silver Hallmarks

Silver Hallmarks and Makers' Marks.

Russian Silver Hallmarks

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."

Useful Items

1. Digital Gram Scales are very inexpensive and common at retail stores. These pocket sized scales are popular with visitors to this site.

View Digital scales .

2. Basic Gold Testing Kits are also affordable, but are more difficult to find at retail stores. The most popular among our visitors is this testing solutions kit which comes with a large touchstone. This pocket key chain/ring is also handy for testing gold.

View Gold testing kits

3.Jeweler's loupes are inexpensive and useful for other work, not necessarily connected to jewelry.

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). New jewelry is typically sold by the gram, but scrap gold is always measured by the pennyweight.

    Gm = Grams

    Oz = Ounce

    ozt = Troy Ounces

    dwt = Pennyweight

    Kgm = Kilogram (1000 grams)

Locating the hallmark

Finding the gold hallmark can be a difficult task. Hallmarks are small and can be very hard to spot. A jeweler's loupe or magnifying glass will help you find these marks. 

This small table will help you locate the gold hallmarks on your jewelry.

Why isn't my jewelry marked?

There are several reasons your jewelry might not show a quality mark (14K, 18K, etc.).

• It may have worn off over the years. This is especially true of rings of high karat gold which is quite a bit softer than the lower karats. Necklaces often have worn clasps which render the mark unreadable, or which were replaced with unmarked ones.
• Brooches were often just marked on the pin shank or catch which may have been replaced due to wear.
• The item may have been repaired and the original mark was removed or destroyed. Rings that have been resized or reshanked often lose their mark or stamp of quality.
• It may have been custom made by a jeweler who didn't have a registered trademark and therefore couldn't legally add a quality mark.
• Some pieces are of such construction, or so delicate, that there just is no way to stamp them. Sometimes, a tiny plate with the stamped mark is soldered on.
• Maybe it isn't made of precious metals.
• Actually, the law doesn't require a mark at all. The legal requirement is that if manufacturers quality mark items of jewelry, they must also include their registered trademark.
• There are weight limits below which items do not need to be hallmarked. For gold this is 1g, silver 7.78g, platinum 0.5g and palladium 1.0g.
• A quality mark, or the absence of one, should not be the sole determinant of an item's metal content. There is little to stop someone buying a jewelry stamp and stamping a piece of gold plated jewelry as 14K or 18K.
• There are chemical and electronic tests that can determine the karat value to within a few percent. Most dealers have one or both of these test capabilities on hand.