Opal Diffusing Glass is similar to ground glass, but with one surface flashed with a milky white "opal" coating to diffuse light evenly. It can be used to achieve a near Lambertian distribution. The level of diffusion in opal glass causes a large amount of scattering loss. Opal Diffusing Glass features more diffusion than a Standard Ground Glass Diffuser. Due to the manufacturing process of the opal coating, the transmission may vary from one production to the next.