Glow-in-the-dark* blue or green pigment is trapped inside a real light bulb (just like the ones you have at home), then the light bulb is encased in a solid block of Acrylic resin. The mysterious optical effect is caused by light diffracting in the tiny space between the glass of the light bulb and the resin, the space forms when the resin shrinks by a tiny amount during the production possess. The polished surface gives a jewel like quality to the object. In a darkened room or at night the Glow Brick comes to life with a tranquil and subtle glow emanating from the pigment inside the light bulb.

*The technical term for the glow-in-the-dark is "photoluminescence" this is a process in which energy absorbed by a substance is released relatively slowly in the form of light.