A watch crystal can vary depending on the model, the brand, and so on. Here's how to tell acrylic, mineral and sapphire crystals apart.
Acrylic crystal
The acrylic watch crystal is an affordable plastic-based crystal - often called acrylic, plexiglass or hesalite. It's light, and easily polished with Polywatch to bring back its clarity and shine. It also reflects light less than mineral or sapphire, making the dial easy to read. The downside: it scratches and chips more easily than the other crystal types.
The acrylic crystal can also be called hesalite. One advantage is that it can be moulded, allowing many shapes that aren't possible with mineral or sapphire.
Acrylic has a Vickers hardness of around 500 - the softest of the three crystal types.
Examples of acrylic watch crystals (non-exhaustive)
Mineral crystal
Mineral glass is the most widely used crystal in watchmaking. It's tougher than acrylic - not a synthetic compound but ordinary glass that has been hardened against impacts and temperature swings. It can still scratch, however, and it's harder to polish than acrylic. With dedicated Polywatch for mineral glass, small scratches are easy to buff out.
Affordable and sturdy, mineral glass can still scratch or chip after a few years. Find mineral watch crystals in our online shop.
Mineral has a Vickers hardness of 650-800.
Some examples of mineral watch crystals
Flat mineral crystal
Domed mineral crystal
Sapphire crystal
Sapphire is the toughest watch crystal in terms of scratches, impacts and breakage. It shares the properties of natural sapphire. More expensive than the other crystal types, it is grown in the lab from aluminium oxide crystallised at high temperature. It's the material of choice on high-end watches - the Omega catalogue, for example. Sapphire crystals may be treated with anti-reflective or anti-scratch coatings. See all our sapphire watch crystals.
With a Vickers hardness of 2300, sapphire is extremely hard - second only to diamond.
Examples of sapphire watch crystals
Domed sapphire crystal
Crystals in our online shop
Every crystal type (acrylic, mineral or sapphire) is available in flat or domed profiles. Find the crystal you need in our Watch crystals section.