Gadolinium gallium garnet (GGG) is a synthetic single crystal with high mechanical and chemical resistance, high thermal conductivity and high thermal capacity. GGG crystals are grown using the Czochralski method. They are considered promising for the production of optical components and substrates for magneto-optical films. It can also be used as an optical insulator formed from a YIG or BIG film on the GGG substrate.

The GGG single crystal is an important substrate for microwave insulators and, thanks to its special thermomagnetic properties, it is used in cryogenics for cooling objects at temperatures close to absolute zero.

Due to its high refractive index, a lens made of gadolinium gallium garnet can replace an entire lens system, which is particularly important in compact devices. Optics made of GGG are used in lasers, telecommunications and electronics.