Blue Lace Agate For Tranquillity. Vibrant, unique and full of style, our iconic MV Siren™ collection brings semi-precious gemstones to life for a fresh everyday look. This delicate MV Siren™ Mini Nugget Cluster necklace features five organic shaped, rose cut Blue Lace Agate gemstones set in Sterling Silver. The necklace measures 34mm in width and 440mm in length and the chain measures 18', a sliding bead allows you to adjust the length down to 17' and 16'.