Flint glass is a type of glass known for its high refractive index and brilliance. It is made by adding lead oxide to the glass mixture, which enhances its clarity and weight. This glass is often used in fine glassware, decorative items, and optical lenses due to its ability to bend light effectively. The term "flint" originally referred to the silica used in the glass-making process, which was similar to the flint stone. Today, flint glass is popular in the production of crystal glassware and fine jewelry, where its sparkling appearance is highly valued.