Image Courtesy of OttoFrei.com.
A lobster claw is a catch used for bracelets and necklaces. It has a spring mechanism which holds the catch closed. Usually, this spring can be temporarily removed when soldering needs to take place. They come in many shapes, but the oval and pear shapes are most common. This snap hook clasp was introduced in jewelry by Cartier1
Alternative names: Cartier clasp, lobster clasp, snap hook.