The Sterling Silver 18 Key Necklace Set With Diamond by Amanda Cox Jewellery. This handcrafted sterling silver key necklace is set with a radiant white diamond and suspended on a 30\" chain. This necklace is designed to be an 18th birthday gift. What better way to mark passing through the doorway to adulthood than with a beautifully symbolic key? This is sure to be a treasured possession. About The Designer: Yorkshire based designer, Amanda Cox has been making jewellery since her sister returned, jewellery clad, from the Isle of Wight Festival in 1970. Starting out with whatever materials she could find, today she utilises only the finest materials for her vintage-inspired pieces. To find out more about the designer please visit Amanda Cox Jewellery.