7 Questions about Gold Plating Answered
Editor’s Note: After publishing an article by gold-plating expert and occasional guest writer, Calla Gold, we received several inquiries. Calla was kind enough to answer the questions below.
The original article: How Gold Plating is Done, Step by Step
- “I have a very collectable and valuable vintage bracelet made of base metal with glass inserts. It has been gold plated once but the coat has worn off completely. If I am to gold plate the bracelet would it have to be taken apart first or can it be plated assembled?”
Gold plating is an immersive process. It’s performed in a heated liquid bath. Your jeweller or plater would need to see the piece in person to determine if the glass needs to be removed. It’s not because of the glass itself, which is nonmagnetic and would be unharmed and left unplated. The potential problem is the glue, which may or may not have been used to create the piece. The plating solution might be contaminated by the glue. For me, that is what I worry about.
- “I am a jewellery manufacturer. We face many difficulties in gold plating and rose gold plating in that it tarnishes very quickly. My clients complain that even 3 micron pieces tarnish in 2-3 weeks. For example, some of the rose gold plating goes black. My clients compare with similar jewellery they have purchased elsewhere that hasn’t tarnished. Can you help explain why there is an issue?”
Different countries do different kinds of plating. Some platers claim they do micron plating, when many times (not all times) they do a “flash” plating. We have a customer that imports kilos and kilos of silver beads and asks us to redo the factory plating on a lot of them because of the thin plating and tarnishing.
The three main issues I have seen with colour plating are:
1. Yellow gold or rose gold plated directly over silver. There should be a barrier of copper or palladium or nickel between the silver and the gold.
2. Too thin a layer of plating.
3. Too much copper in the rose gold plating mix, to make it pink. Copper tarnishes quickly and there’s a fine line in the chemistry of the plating baths. Too much copper and the rose gold will darken too quickly.
Some manufacturers are great at colour plating and very thin plating. Others are great at clear coating and E coating. This makes their plating last almost forever, and it won’t change colour, because the clear coating seals the piece of jewellery from the air.
- “How can you determine if a piece is real gold or other precious metal? Or if it’s plated or there’s lead in the jewellery?”
XRF (X-ray fluorescence) technology is a non-destructive analytical technique used to determine the elemental composition of materials. There are portable XRF analysers that can perform fast, accurate, and most importantly, non-destructive analysis of the precious metals. These gold spectrometers quickly provide the exact karat weight and percentages of all elements within an item – easily identifying non-standard, under-karated, and even advanced counterfeit gold with fire assay-comparable accuracy. They can quickly distinguish between gold plating and solid gold, as well as determine the presence and concentration of other trace alloying elements and dangerous heavy elements (like lead) which could impact valuation and future refining needs.
- “Can the electroplating process be reversed? I have circuit boards with gold on them. Can I use this process to take the gold off the circuit board and deposit it on a piece of gold wire?”
It is possible to use reverse current to plate off the gold from the circuit boards. However, other materials on the circuit boards may be plated off as well so if you want only pure gold plated on the wire, which may be a problem. If you are going to melt, refine or assay the wire then it shouldn’t be a problem.
- “What happens to the plated gold after the old jewellery is cashed in?”
A great deal of jewellery is made with just a layer of gold on the surface over another type of metal underneath. For example, gold vermeil jewellery uses sterling silver which has been gold plated. Some gold-plated jewellery uses a base metal, such as copper or nickel, which is then electroplated with gold. For gold-plated items, their plating can vary in thickness, and no minimum value needs to be met for a piece of jewellery to be sold as gold plated.
The problem with trying to cash in these jewellery pieces is that the other alloying elements are not as valuable as gold, so the refiners need to separate them out and then evaluate just how much that heap of gold, other precious metals, and alloy materials is actually worth. (Hopefully the store operator who analysed the jewellery pieces used an XRF analyser to ensure the right value was assigned to the piece before giving out any cash to the customer.) Read more about assaying and assessing the jewellery.
- “I have a pair of earrings and I would like to have them gold plated. I have noticed a slight difference in colour where the prong is soldered to the base of the earring. Will the gold plating cover the colour difference making just that spot more uniform?”
My short answer to the question is that gold plating is immersive and will be the same colour regardless of subtle colour differences on the underlying metal. With silver that has been gold plated, oxidation can cause the gold plating to darken in spots. If the other coloured metal in your earrings is a metal that oxidizes, then it is possible that over time that oxidation could show up as darker, like a shadow in the gold plating.
- “What’s the difference between Electroplating and PVD Coating?”
See separate article on Calla Gold’s website: Gold Electroplating vs PVD Coating