Crystal

The crystal is the transparent cover over the dial. Modern luxury watches usually use sapphire crystal; older watches often used acrylic.

The material affects both durability and value: sapphire resists scratches well but can shatter, while acrylic scratches easily but can be polished, and collectors of vintage pieces often want the original type.

Check the crystal for chips, cracks, and deep scratches at intake, and whether it's the correct type for the reference.

A replaced crystal is a routine part of servicing, so its presence isn't a problem on its own; what matters is whether it's the right type and fit for the watch.