Metal Markings & Stamps

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Vintage Jewellery Metal Markings and Stamps

Scroll below for explanations of the different types of gold, silver, etc.

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Common Markings
.333 8kt gold
.375 9kt gold
.417 10k gold
.585 14k gold
.750 18k gold
.999 24kt gold
PLAT platinum
.925 sterling silver
PALL paladium
IRID iridium

We hear these terms used everyday, but what do they really mean? Solid, pure gold is 24K. Anything “less” than that has some kind of other type of metal mixed into it – called an alloy. Because pure gold is so soft – this alloy helps to strengthen it (10K gold is stronger than 14K gold, which is stronger than 18K gold). This alloy is also how manufacturers can create different colors of gold: red, pink, blue, green, shades of yellow, even violet! Just because gold is a different color than the standard “yellow” doesn’t mean it is a “lesser” quality of gold.

(Percentage of 1,000 parts)
9K          .3750
10K         .4167
12K         .5000
14K         .5833
15K         .6250
18K         .7500
20K         .8333
22K         .9167
24K         1.000

For those of us living in Australia, the UK or other countries of the Commonwealth, 9ct gold is the most common fineness of gold jewellery found on the market. Below are gold finenesses used for jewellery making and their equivalents in percentage.

  • 8ct, 8K or 333 stamped items are 33.3% in gold fineness
  • 9ct, 9K or 375 stamped items are 37.5% in gold fineness
  • 10ct, 10Kor 416  stamped items are 41.6% in gold fineness
  • 14ct, 14K or 585 stamped items are 58.5% in gold fineness
  • 18ct, 18K or 750 stamped items are 75% in gold fineness
  • 21ct, 21K stamped items are 87.5% in gold fineness
  • 22ct,22K or 916 stamped items are 91.6% in gold fineness
  • 23ct, 23K or 965 stamped items are 96.5% in gold fineness
  • 24ct, 24K or 999 stamped items are 99.9% or described as PURE gold

Some karatages of gold are only available in some parts of the world –

  • 8ct gold, which is usually stamped 333 is as far as I know only used in Europe- especially Germany
  • 10ct gold is widely used in the US and Canada, but as manufacturers or wholesalers can market there items anywhere nowadays, it is also seen in other parts of the world
  • 21ct gold items are mostly produced in Arab countries, and usually the stamp is in Arabic numarals, so you might see instead of 21ct a vertical line and a V (like lV)
  • 23ct is widely spread in Asia, though more common in Thailand, as other asian countries prefer either pure 24ct gold, or 22ct gold

Newer gold filled items have markings that indicate how much and what type of gold was used for the layer. A marking that says 1/20 12K G.F. means that the jewelry is at least 1/20th 12K gold by weight.  The gold layer in gold filled items is typically thicker than the gold in gold plated items.

The gold layer in gold plated jewelry is typically thinner than the gold in gold filled jewelry, so it usually wears away more quickly. Plating is done in different ways.

You may also see terms such as gold washed used to describe a very thin layer of gold – one that won’t be very durable.


  • 24K gold is pure gold.
  • 18K gold contains 18 parts gold and 6 parts of one or more additional metals, making it 75% gold.
  • 14K gold contains 14 parts gold and 10 parts of one or more additional metals, making it 58.3% gold.
  • 12K gold contains 12 parts gold and 12 parts of one or more additional metals, making it 50% gold.
  • 10K gold contains 10 parts gold and 14 parts of one or more additional metals, making it 41.7% gold. 10K gold is the minimum karat that can be called “gold” in the United States.

European gold jewellery is marked with numbers that indicate their percentage of gold, such as:

  • 18K gold is marked 750 to indicate 75% gold
  • 14K gold is marked 585 for 58.5%
  • 12K gold is marked 417 for 41.7%

EBAY GUIDE – pawnbrokersworld

  • Gold Wash or Flash gold. This form of plating uses the minimum of gold. An ultra thin coating of electroplate gold of maybe ½ micron if you’re lucky (1 micron is 1 millionth of an inch). This jewellery is not normally marked with any hallmark and will come off with the slight wear. Used on bling bling cheap jewellery and does not conform to any standard.
  • Electroplate. (EP,GP) Normal electroplate jewellery puts a layer of between 1 to 20 microns of gold on a base metal article. Depending how thick the plating is, will determine how long a piece will retain its shine. 20 microns is good and used on watch cases with a 20 year wear guarantee. Pieces may be marked with GP after the carat of gold used. E.g. 18K GP some include the thickness of the plating e.g. 18K GP 10 Microns
  • Hard Gold Electroplate. (HGP, HGEP) Same as above but even thicker. 100 microns of gold is used in this electroplate process. This is the best type of electroplate and is marked usually something like this 18K HGEP or HGP. Found on heavy use articles like gold spectacle frames, watch cases etc.
  • Rolled Gold, Gold Overlay. (RG, OG, GO) This is not a plating process but a fusion process where a sheet of base metal is covered with thin layers of gold and then heat fused together. Jewellery is then made from this sheet. There is usually an indicator number to tell you how much gold was used. E.g. 1/40 18K RG means that an 18K layer has been fused to a base metal AND that 1/40 of the total weight of the piece is 18k gold.
  • Gold filled. (GF). Same as rolled gold except it meets a higher standard, in that it has to be 1/20 gold as against the weight of the article. You may see 18K GF or 1/20 18K GF. They both mean the same. This is the best form of plated gold. It should last at least one lifetime and more.
  • SOLID Gold. ( *K, *KT, *ct *CT ) Most people are familiar with gold marks. They can range from 8K to 24K (333 to 1000). There are various ways to indicate the purity of gold. Most are controlled by your government and are to certify that the piece of gold you have falls into an acceptable range of purity. See my other guides if you want an in depth look at gold markings.
  • Plumb Gold ( *K P ). Very rarely seen but the P after the carat designation means “plumb gold”, which means the purity is EXACTLY as stated and does not allow any variation. Most unusual for jewellery. E.g. 18K P
  • Gold Plate on Solid Gold. Some jewellers use a high carat plating on a lower carat gold piece to enhance the colour. Unfortunately there is nothing to indicate this process as there is nothing illegal in this form of plating. If you see a 9K piece of jewellery that is a very bright yellow you may be suspicious, but that’s it. It still 9K gold but which, over the years, may lose its bright yellow appearance. There are no Hallmarks for this.

If you like antique jewellery, rolled gold and gold filled are well worth considering as they were very popular in the 1800’s with a lot of good jewellery manufactured from it. Such a thick layer of gold means many of these old pieces are still good condition.

  • The “CT” hallmark is generally an older hallmark than the “K” in gold.
  • “15ct gold” is a pre 1935 mark, so neatly all 15ct gold as at least that old.
  • “1/20” is used to signify early rolled gold, eg 1/20th 9ct. Some beautiful thing were made from rolled gold in the 1800’s.
  • “Peridot”, “garnet”, “seed pearl” were popular in old jewellery.
  • “Old cut”, “mine cut”, “rose cuts” were all old forms of faceting gems.
  • “Rose” gold we all know about.
  • “Art” covers both Art deco and Art nouveau.
  • “Enamel” always brings up interesting things.
  • “9ct” or “9K” is always an interesting search on the US eBay site, as their minimum gold standard is 10K. You don’t find a lot but what you do can be interesting. Also try Canada or North America for 9ct gold, being a past member of the British Commonwealth.

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