This Necklaces glow in the tark like a moon, after they absorbed enough light. So please make sure that you have put necklace under the light to absorb light before you enjoy their light in the dark. The longer they exposed, the stronger they Glow. Material: Environmentally friendly material alloy, Lead-Free,Nickle-Free and Cadmium-Free Anti-allergic and no harm to health. White Gold plated,keep the color not easy to fade, Comfortable wear it.