Hi Rosie. I think you're talking about the Clic-Clac, also known as the H. Bracelet due to the "H" clasp. They come in two different widths and also two different sizes - PM and GM, so they'll fit a variety of wrist sizes. They're made of very high-quality Austirian (I think) enamel and base metal with either a 24K. gold plating or a silver/palladium plating. Hermes' plating is excellent, and the finish should not wear or tarnish.
Enamel does chip, and Hermes advises not to wear chain bracelets with their enamels, but I think you can stack other bangles as long as they don't chink together.
The wider Clic-Clac is around $570 US I believe, and the narrower one is slightly less at around $540 US. (Someone will give you the accurate price if I'm wrong here.) They come in a wide range of bright colors and neutrals, and the boutiques usually have a good supply.
They are one solid color, however, with no pattern. The patterned enamel bangles are a whole other animal, and one I'm not too familiar with, I'm afraid.
The Clic-Clac is great though and a wonderful first Hermes piece. Hope you find the one you want under the tree!