Jewellery is one of the oldest forms of human adornment and fashion, with evidence of jewellery dating to over 100,000 years ago. Jewellery has come a long way from the early pieces crafted from teeth, shells and other primitive materials; however, some ancient materials and techniques have stood the test of time, and are still used today in jewellery production. Types of jewellery, e.g. necklaces and earrings, tend to be purely for ornamentation, whilst others can serve symbolic or practical purposes. For example, signet rings have been used for thousands of years to mark wax with a seal and to present a personal or family crest. Hair pins and brooches have also served functional purposes, being used to secure hair or fix clothes. For centuries, rings have been considered a symbol of love, with couples gifting one another promise, engagement, wedding and eternity rings.