In watchmaking, the term "crystal" refers to the transparent cover that protects the watch face. There are three primary types of crystals used in watches: sapphire, mineral, and acrylic, each offering distinct characteristics.

Sapphire crystal is highly prized for its exceptional scratch resistance and durability. Made from synthetic sapphire, it is second only to diamond in hardness, making it an ideal choice for high-end watches. Its clarity and resistance to shattering make it a preferred option for luxury timepieces, although it can be more expensive than other materials.

Mineral crystal, on the other hand, is made from glass that has been heat-treated or chemically treated to enhance its scratch resistance. While not as hard as sapphire, mineral crystal is more affordable and offers a good balance between durability and cost. It is commonly used in mid-range watches and provides adequate protection against everyday wear and tear.

Acrylic crystal, also known as plexiglass, is a type of plastic that is lightweight and shatter-resistant. It is the most affordable option and is often found in entry-level watches or vintage models. While it is more prone to scratches, these can often be polished out, making it a practical choice for those seeking a cost-effective solution.