So not what I had hoped for. I placed these stones in direct sun...I live in LA so in the land of perpetual sunshine, especially July, these should really glow. Yes, the emit an ever so tiny glow that if you are standing right over them is visible, but from the distance (eg, house to garden where they are placed), nada. Very disappointing. Also, if you are seriously looking at purchasing this type of item, 100 stones despite the triple digits look pretty inconspicuous. Would not recommend.