Glow-in-the-Dark Zodiac Pendant Necklace - Starry Sky Glass Ball with Luminous Constellation Design, Fashionable Zinc Alloy Jewelry for Men

The picture inside the product is made of fluorescent material. If you put it directly in the dark, it will not emit light. The correct way to use it is: put it in the dark and illuminate the product with a flashlight or light for 10 seconds, make it absorb the light, then turn off the light, you will find it glows in the dark