UMBRELLALABORATORY Wishing Square box Magical Fairy Glow in the Dark Necklace-blue-sil Magical Glow in the dark necklace Rare Handmade Pendant is roughly 13x13x13mm, necklace chain is 18" long. Any light will charge the powder. However, direct sunlight, high wattage bulbs, or black lights are needed to obtain the maximum glow. The glow will gradually fade until recharged. It can be recharged over and over. Tool for any crazy time traveler