The watch crystal is the transparent cover that sits over the watch dial, protecting the face from scratches, dust, and moisture. Despite the name, most watch crystals are not made from actual crystal – the term refers to the shape and clarity of the material, not its composition. Watch crystals are manufactured in three main materials: acrylic (also called hesalite or plastic crystal), mineral glass, and sapphire crystal, each offering a different balance of scratch resistance, clarity, and repairability.
Acrylic crystals are the most affordable and were standard in watches made before the 1980s. They scratch easily but can often be polished back to clarity, making minor damage reversible without full replacement. Mineral glass crystals are harder than acrylic and offer better scratch resistance, but they shatter more readily on impact and cannot be polished. Sapphire crystals are the premium option used in high-end watchmaking: sapphire rates a 9 on the Mohs hardness scale, making it nearly as hard as diamond. Sapphire resists scratches effectively but can crack under a sharp, focused impact. Because of its hardness, a scratched sapphire crystal typically cannot be polished – replacement is the only option.
A cracked, deeply scratched, or shattered watch crystal affects more than aesthetics. Moisture and dust can enter the case through a compromised crystal, damaging the movement over time. QJR's watch repair technicians replace acrylic, mineral, and sapphire crystals across most watch brands and styles. If a crystal is cracked or scratched to the point of affecting legibility, replacement is always the right call – crystal replacement is one of the most cost-effective watch repairs available.