Jade necklace is tight and loose, because people's skin will relax when it is hot, and they will feel the necklace tight. Jade is a mineral. There are two kinds of jade: soft and hard. Usually, jade refers to nephrite. It belongs to one of the most common jewels. According to "Tengyue Local Records" written by Qing Jinshi Cun Kaitai, "Tengyue is a collection of jade articles, made into utensils and sold to various provinces in Yunnan. Top grade jadeite is mostly sent to eastern Guangdong, Shanghai, Fujian, Zhejiang and Kyoto.