Natural Fluorescent Stone Luminous Angel Necklace $ 4.26 Material: Alloy Chain style: cross chain Pendant material: alloy Circumference: 21cm (inclusive)-50cm (inclusive) Color: NY639 White K+Blue Green, NY640 White K+Sky Blue, NY641 White K+Yellow Green Luminous light is not a natural luminescence, it is a physical property, it shines after absorbing light Absorb sunlight, ultraviolet rays, sun light, flashlight Use strong light for about 10-20 minutes. The longer the irradiation time, the brighter the night light. The duration is about half an hour. Wait for the light to dim, then use the light Can be used repeatedly forever (the purple one needs to be irradiated a little longer).