Transparency is the degree to which light is transmitted through a gemstone.
The terms used to differentiate the degree of light transmission through a gemstone are:
- Transparent. Light passes through relatively unobstructed. An image or object can be seen through the gemstone with very little distortion (other than due to facets or double refraction).
- Semitransparent. Light passes through but is slightly diffused. An image or object can be seen through the gemstone but with an indistinct outline or slightly distorted.
- Tanslucent. Light passes through but objects cannot be distinguished through the gemstone.
- Semitranslucent. Light passes through only at the thin edges of the gemstone.
- Opaque. No light is transmitted through even at the thin edges of the gemstone.