Jewelry has been an important part of the Chanel look ever since the beginning. Chanel herself was known for really piling on jewelry. She wore multiple strands, pearls, some of which were fake. She mixed fine jewelry and costume jewelry. She was one of the real pioneers in wearing showy costume jewelry during the day.
During that time, it was considered kind of bad taste to wear colored stones during the day; emeralds, sapphires, rubies, etc. Chanel herself had a fantastic collection of fine jewelry. Some of the pieces were gifts from lovers and friends and some of which she acquired herself. But, she built a relationship with a costume jewelry company to produce great looking pieces for Chanel early in her career.
Chanel was also known for wearing heavy cuff bracelets, some of which had a Maltese cross on them. And the cuff bracelets were designed by her friend Fulco di Verdura who had a really important jewelry company because Chanel was always her own best model. Her personal style of wearing jewelry has become an integral part of the Chanel look.