Crystal is a type of glass that is made from a combination of sand and other minerals. The most common types of crystal are lead glass, flint glass, and crystal glass. The main difference between each of these types of crystal is the amount of lead oxide in the mixture.
Crystal has a high refractive index. It is often used to make jewelry, but it’s also popular for use in lighting fixtures. Because it’s highly refractive, crystal can be used in lighting fixtures to create a wide range of effects, from creating a soft glow to making the light appear very bright and sparkling.
The quality of crystal depends on its purity: if there are impurities present in the mineral, then it will not have as much refractive power as pure crystal does (and therefore won’t be able to reflect light as effectively). This means that you should try to buy only high-quality crystal if you plan on using it in your lighting fixtures so that those fixtures will produce optimal effects.