So what is it? Rhodium is a chemical element and part of the platinum group of metals.
The platinum group is comprised of six metallic elements in total and is sometimes subdivided further into iridium-group elements and palladium-group elements.
Rhodium is a member of the latter.
These six members of the platinum group lie together in the periodic table of elements and share many of the same chemical and physical properties.
Discovered in 1803 by a William Wollaston, rhodium was initially not used for a great deal.
It has found far greater popularity in more modern times however, specifically in the areas of jewelry and automobiles.
In the latter case, it is used as one of the catalysts in catalytic converters, devices that form part of the exhaust system and convert toxic gases produced by the engine into less harmful substances by way of chemical reaction.
More than 80% of the world's rhodium (as of 2007) is put to use in this way.
Rhodium in jewelry The use of rhodium in the crafting of jewelry is perhaps where it is most well known.
Specifically, rhodium is most commonly used to plate white gold; the brilliant shine of the rhodium obscures the less pure color of the gold alloy beneath.
Indeed, the very common misconception about white gold - the name being a misnomer in itself - is that the color you see is the color of the gold when in reality it is simply the rhodium.
With general day-to-day use, the surface of any white gold jewelry will eventually get eroded, exposing the creamy golden color of the gold alloy beneath.
Getting the jewelry re-plated with rhodium is generally not an expensive affair, though it must be noted that the quality of the gold alloy will determine how often the piece will need re-plating and subsequently how expensive this will be.
Rhodium-plated platinum is a rarer sight than white gold on account of it being considerably more expensive.
The reasons for plating platinum are exactly the same; the color of rhodium is purer and more brilliant than that of platinum, therefore making it more desirable.
Sterling silver jewelry is also sometimes plated with rhodium, although the reasons for doing so are slightly different.
A rhodium plating protects silver jewelry from tarnish, a common occurrence that happens when the silver reactions with sulphur-containing substances in the air.
The use of a rhodium plating may slightly increase the price of the silver jewelry.
You will rarely - if ever - come across jewelry created solely from rhodium.
Quite apart from its high price, rhodium has very poor malleability, making the crafting of jewelry extremely difficult and less commercially viable.
What other uses does rhodium have? Although the main uses of rhodium have been described already, it possesses additional qualities that make it useful in other areas.
Due to its low electrical resistance for example, it is sometimes used as an electrical contact (a switch in a circuit that can be opened or closed).
Another positive quality of rhodium is its high corrosion resistance.
This makes it ideal for use in alloys that are then used in many things, from aircraft spark plugs to furnace bindings.