Q: What is the difference between glass and crystal?
A: Crystal is made by adding lead oxide to glass. The lead in crystal is what makes it sparkle and reflect colors so much more than plain glass. It also makes crystal heavier than glass. The higher the lead content, the better quality the crystal. In Europe, glass must contain at least 4% lead to be called crystal and in the US, glass must have at least 1% lead content. In contrast, Swarovski crystal has at least 30% lead content.