It's not an optical illusion; it is our Optic Crystal Glass Bottle Stopper! Shimmering, shining and just gorgeous! The color changes with the light, making each stopper its own unique vision. Dress up your wine bottles, liquor bottles, oil bottles and your favorite decorative bottle. This 4.25" stopper with metal base (rubber gasket to keep your liquids fresh) will add panache to every room in the house.