To make a piece of jewelry it will be necessary to bend, mould or form the raw material which is usually precious metal wire,sheet or rod into both decorative and functional shapes such as rings or pendants and this process is known as forming & forging. Pliers can be used to form basic shapes with thin wire but most shapes are formed using hammers & mallets and steel or wooden forming blocks often called blocks, stakes, mandrels & triblets.
There are hundreds of hammers available but the two most common and popular hammers used by jewelers are the raw hide mallet (some prefer similar plastic versions) and the planishing hammer. The raw hide mallet with a head made of leather will form wire or sheet around a steel triblet or mandrel etc. and the raw hide do it with very little marking to the metal surface so you can get a beautiful flat mirror finish on pieces formed using a raw hide mallet with very relatively little filing or polishing after forming. The planishing hammer has a steel head with one flat and one slightly domed surface will form shape faster than a raw hide but marks the metal significantly either with a series of flats or dimples which will take significantly longer to remove using emery paper of files than if the piece was formed using a raw hide mallet.
A popular technique is doming and dapping using doming punches and doming blocks and dies to produce concave and convex dished or domed shapes.
Anticlastic shapes are formed using sinusoidal shaped stakes, an anticlastic shape is one where the two dominant axis are curved in opposite directions and the best example of one is a horses saddle.
Bangles and cuffs are very popular and very easy to form anticlastically using concave forming dies which form both curves simultaneously.