Inner circumference: Approximately 15.5cm, with some margin of error. * If you wish to change the size (up to 17cm free of charge), please let me know, even after purchase. White Moonstone: 10mm 64-facet cut Crystal: 6mm Crystal: 6mm Aquamarine: 6mm Amethyst: 4mm Double-strand Ope-ron rubber * The rubber knot is not fixed with adhesive. If it comes out, gently pull it back in from the opposite side of the stone. The stones may have small scratches, inclusions, color variations, dents, and natural cracks. This is handmade by an amateur, so please refrain from purchasing if you are looking for perfection. 96