One metal sphere contrasts a string of celestial gemstones. Easy to wear, this stackable design stretches. Gemstone: Black Onyx (Semi-Precious). Our semi-precious gemstones are rare, ethically sourced and hand cut from naturally occurring materials, giving each individual stone its own unique colour. Note: stone colour per piece may vary. Bead Diameter: 8mm Circumference: 20cm / 8"