What does single refraction indicate about a gem's optical property?

Single refraction in a gem's optical property indicates that when light enters the gemstone, it refracts in only one direction, which means that it does not split into multiple rays or colors as it would in the case of double refraction. This characteristic typically applies to isotropic materials, where the refractive index is the same regardless of the direction in which the light travels.

When light encounters an isotropic gemstone, it passes through without altering the number of light rays or creating dispersion, which means the gemstone does not separate light into its constituent colors. Therefore, the process primarily involves the refraction and absorption of the incoming light without producing additional complexity in how the light is transmitted through the gem. This property is fundamental in identifying the optical behavior of certain colored stones and assists gemologists in the classification and evaluation of gemstones.