Kyanite For Loyalty. Vibrant, unique and full of style, our iconic Siren collection brings semi-precious gemstones to life for a fresh everyday look. This delicate Siren Mini Nugget necklace features one organic shaped, rose cut Kyanite gemstone set in Sterling Silver. The necklace measures 8.5mm in width and 440mm in height and the chain measures 18', a sliding bead allows you to adjust the length down to 17' and 16'. Every hand-crafted Monica Vinader piece comes with a 5-Year Warranty and lifetime repair service.