Rose gold is an alloy consisting mostly of gold and copper. The copper gives it it's lovely reddish edge, mixed with the yellow of the gold.
Technically rose gold should have less copper than red gold, but most people use the terms interchangeably. Rose gold often used to be referred to as Russian gold, but that term has fallen out of use.
The colour and the metal is a huge current trend, with all kinds of things available in the metal itself, or in the colour. It's a wonderful warm, flattering metallic, the 9ct rose gold I sell my skinny rings in is very soft and elegant. The rocking wishbone below is in 9ct rose gold. Below are also some gorgeous rose gold items I have come across.
This lovely fossil watch in rose gold would go with all the jewellery in my box, silver or gold.
These fisherman sandals from American Eagle Outfitters are also a lovely soft colour which would go with most of my wardrobe.
And last but not least is this lovely rose gold belt from Anthropologie. This would be so pretty with a plain black or white dress.