Perhaps you would like to hear about the benefits of rhodium plating before understanding what it is.
1. I am allergic to silver but want to wear white coloured metal
Those of us who have allergies to silver, are keen to find alternatives. If you belong to the unfortunate few who is allergic to even the hypoallergenic steel ear posts, you should try rhodium plated earrings. It seems the allergy maybe triggered by the alloys (nickel) that are used both in silver & steel.
You should be fine with yellow gold since most people aren’t allergic to it as it’s an inert metal. But that of course isn’t the answer if you don’t want to wear a yellow coloured metal. We wouldn’t recommend white gold since it is a mix of gold with other alloys including nickel. By the way, there are those who have allergies even with pure yellow gold sometimes! So if haven’t already, you may want to give Rhodium plated jewellery a go. But each person’s allergies are so different this is more a suggestion to try than a recommendation!
2. I would like a brilliant mirror silvery sheen without any discolouration please
If you are fed up with having to clean tarnish of those brilliant white silver pieces of yours, and all you want is the colour, you can look at rhodium plated sterling silver. Many of us like brilliant shine that rhodium plating provides. So actually rhodium plating is often applied to white gold to keep the dazzling sheen.
3. I want something less expensive than platinum and white gold without either of the two problems above
Rhodium plating on metals like brass will look just like a top end platinum or white gold counterpart without the hallmarking. So if you are after the look without the price then you might want to consider rhodium plating on metals such as brass or steel.
So now what is rhodium plating?
Rhodium is the one of the most expensive metals in the world. And rhodium and platinum metals are cousins ;-).
Rhodium by itself is kind of impossible to create jewellery with because it’s brittle and doesn’t lend itself to jewellery making in a solid form. But because of its hard finish and brilliant sheen it works well on another metal. So rhodium is layered on through a process called electro plating. This is a process where the metal to be plated is put into a rhodium bath solution and an electric current passed through the bath. This causes a bonding between the rhodium and the metal. So a very thin layer is plated on top of the other metal.
Do remember that since this is a very thin layer, it will need re-plating periodically depending on the usage of piece in question.