A necklace is a piece of jewellery worn around the neck. Necklaces of different lengths have different names: <ul><li>dog collar: below 25cm (10 inches)</li><li>choker: 25cm – 35cm (10 to 14 inches)</li><li>princess: 36cm – 50cm (15 to 19 inches)</li><li>matinee: 51cm – 64cm (20 to 25 inches)</li><li>opera: 65cm – 91cm (26 to 36 inches)</li><li>rope: above 92cm (37 inches)</li></ul>
Gold or sterling silver that is ALLOYED without using nickel, because some people have allergic reactions and/or skin irritation when wearing the metal.
The noble metals are gold, platinum, and silver. These are metals that are relatively impervious to chemical actions: oxidation and corrosion.