Amber is tree sap that's been fossilized over eons. Oftentimes, this fossilized resin includes insects, such as ancient ants, flies, or mosquitoes that lived millions of years ago. The allure of amber has to do with its timelessness but also its pretty glow, which is attributable to the stone's phosphorescent properties. Just like the rare white version of the stone, Amber Thinking Putty starts out white and glows like the golden version in the dark. There is a power to darkness that brings things normally unseen to light. That's the principle behind our Glow in the Dark Thinking Putty. Plain white in daylight, these putties come alive with hypnotic colours that magically appear in the dark. Expose them to light (the brighter the better) and they will glow for hours.