Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical glass. In past decades, it was a popular material used to create decorative vases and bowls as well as crystal glasses and decanters. Lead glass is also known as X-ray glass or radiation shielding glass as one of its major applications is in the absorbance of high energy radiation while maintaining optical transparency. Also, lead glass has a lower thermal conductivity than lead-free glass. Interestingly, even though stained glass windows are a type of leaded glass, industry experts often use them separately to create distinction between the two.

It's the surface of an object that reflects some colors and absorbs all the others. We perceive only the reflected colors. Perceived color depends on how an object absorbs and reflects wavelengths. Human beings can only see a small portion of the electromagnetic spectrum, from about 400 nm to 700 nm, but it’s enough to allow us to see millions of colors!