Vermeil: 18k White Gold Beads: Authentic Firefly Glass Cord: Clear Elastic Cord Size: 7.8" Circumference Base: .925 Sterling Silver Time to #GLOWUP This is Firefly Glass, It's designed by NOGU Studio in Toronto. Nope, there are no electronics involved. The bracelets are made of genuine lampwork hand-blown glass and once energized under a light source emit a spectacular glow. They are the grown up luxury version of your favorite glowing baubles as a kid. During the blowing of the glass, small phosphorescent particles are suspended inside the glass and when charged explode with a brilliant sapphire glow. They are handcrafted in .925 Sterling Silver & beautifully gift boxed.