18ct gold vermeil aqua chalcedony march birthstone necklace on medium plain chain. March: aqua chalcedony, in a light green hue, aqua chalcedony is thought to increase endurance and vitality. The march birthstone also promotes emotional balance, kindness and friendliness. Metal: 18ct gold vermeil on sterling silver. Dimensions: pendant: 18 mm x 15 mm. Plain chain: total length: 450mm with extension links at 410mm/430mm/460mm. Weight: 2.9 g.