1. If it is a round snap necklace, it can be directly buckled into the back ring. If it is a lobster clasp necklace, one hand can be kept open, and then the other end can be wound in, thus shortening it.
2. If it is a splayed buckle of a gold necklace, it can be broken by the elasticity of metal and then folded back, or it can be broken and then wound around a section and then closed.