Gold? Solid, Filled, Rolled, Plated? What do they mean?
As a pawnbroker and secondhand dealer I would like to share some of my experiences in handling gold with you. There seems to be a lot of confusion about what various forms of plating and marks actually mean. These terms are used by many without a real understanding of what they actually mean.
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.
LASTLY, I point out that I am not a jeweller and that the above guide is just that, a guide. I am a pawnbroker with 25 years experience. If you want professional advice go to a jeweller.
SEE MY OTHER GUIDES FOR OTHER INFORMATION ON JEWELLERY. Vote as appropriate.
© 2008 Edward Vabolis