Kyanite For Loyalty. 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 necklace on features one organic shaped, rose cut Kyanite gemstone set in 18ct Rose Gold Vermeil on Sterling Silver. The necklace measures 8.5mm 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'.