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. 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.
Fineness represents the purity of precious metals expressed in parts per thousand.
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.
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.
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.
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'.
Quality marks for sterling silver include:
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 SystemsThe Troy system is often used to measure precious metals and gemstones.
The Metric sytem is also used
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.Abbreviations:
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.).