There seems to be a lot of confusion about what’s what with gold. Is it solid, plated, rolled, etc.
Please use this guide, as just that, a guide and NOT professional advice.
From worst to best…
Gold Wash or Flash gold. This form of plating uses the minimum gold. A ultra thin coating of electroplate gold of maybe ½ micron if you’re lucky (1 micron is 1 millionth of an inch). This stuff is not normally marked with any hallmark and will come off with the slightest 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 very good and used on watch cases with a 20 year wear guarantee. Pieces may be marked with GP after the Karat 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 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. 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 the BEST form of Gold plating. It should last at least one lifetime.
SOLID Gold. ( *K, *KT, *ct *CT ) Most people are familiar with gold marks. They can range from 8K to 24K. 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 articles if you want an in depth on gold markings.
Plumb Gold ( *K P ). Very rare but the P after the Karat 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 on Gold Plate. Some jewelers use a high Karat plating on a lower Karat 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 appearance. There are no Hallmarks for this.
They are the main forms of gold jewellery and plating.. As far as I’m concerned the only real gold jewellery, is solid gold jewellery, all the rest being costume or imitations. That should not stop you buying them if YOU like them, as long as you are aware of what you are buying.
See my other guides on gold to look at other aspects of the precious metal and what to look for.
Thank you for looking.