Pure silver does not tarnish but is too soft on its own to be used in jewellery making. Sterling silver is 92.5% pure silver and 7.5% other metals (often copper) with the ‘other metals’ being used to make the sterling silver harder and thus suitable for jewellery making. It is the ‘other metals’ that oxidize and cause tarnishing of the sterling silver.
Rhodium is a member of the platinum group of metals and, as of May 2011, costs over 50 times as much as silver! It is around seven times harder than silver but only reflects around 75% of incidental light compared to silver’s 95% and therefore appears less shiny. Silver can be given a fine plating of rhodium to add a degree of scratch and tarnish resistance to an item of jewellery, although at a financial cost given the high price of rhodium and the work involved in the plating process.
Pros and Cons
Initially, the rhodium plated piece may appear somewhat less shiny than the equivalent plain silver piece due to the less reflective nature of rhodium compared to silver. However, unless the plain silver piece is kept well polished, over time the anti-tarnish properties of the rhodium plating will make the plated piece appear shinier. Additionally, unless you were to place two similar pieces side-by-side for comparison purposes, one rhodium plated and the other not, it’s doubtful that you would notice that the plated piece was not quite as shiny as it could be.
Sometimes, it’s the case that it would be difficult to clean the silver even if you wanted to. Delicate silver filigree can make cleaning impractical and gem stones mounted within the jewellery can be affected – even damaged – by certain cleaning agents. Rhodium plating the silver can be the best option in these circumstances.
Although rhodium is a hard metal, the very thinness of the layer of plating (around one four-hundredth of the thickness of a human hair) means that the degree of scratch and abrasion resistance it offers is limited (but nevertheless useful). That thinness also means that, even with just normal wearing, the rhodium plating will eventually wear off over a period of time leaving unsightly patches on the jewellery’s surface. Jewellery can be re-plated but this is often too expensive for anything other than a most treasured piece. Additionally, if a rhodium plated piece of jewellery does become scratched or abraded, it is not so easy to repair since the whole piece may need re-plating after the repair is done.
So, is rhodium plating silver jewellery a good or bad idea? Well, as usual, it all depends. If you really hate cleaning your jewellery, then rhodium plating may be just the thing you’re looking for. However, be prepared to throw the jewellery away once the plating starts wearing off – or stand the cost of having it re-plated. If you don’t mind cleaning your jewellery, then you will have a shinier piece than could ever be achieved with rhodium plating and which, over time, will develop that beautiful patina that is unique to you. It seems that there really is no such thing as a free lunch!