Crystal
A watch crystal is the transparent cover that protects the dial. Three materials are common: sapphire crystal, the hardest and most scratch resistant though costly; mineral glass, cheaper and more prone to scratches but better at resisting shattering; and acrylic, soft and scratch prone yet able to be polished out. An anti-reflective coating cuts glare.
At a glance
- Function
- Transparent cover protecting the dial
- Common materials
- Sapphire, mineral glass, acrylic
- Shape
- Flat or domed
A watch crystal seals the dial against dust, moisture, and the knocks of everyday wear, so it shapes both readability and durability. The material a maker chooses affects everything from the price of the watch to how it ages on the wrist.
The common materials
Three options dominate, each with its own trade-off:
- Sapphire crystal: the hardest choice and the most scratch resistant, though also the most expensive
- Mineral glass: more affordable and easier to scratch, yet better at resisting shattering
- Acrylic: soft and scratch prone, but light scratches can be polished out
For a closer look at the two harder options, see our entries on sapphire crystal and mineral crystal.
Shape and coating
A crystal can be flat or domed, and a domed profile gives a distinct look from certain angles. An anti-reflective coating cuts the glare off the surface, making the dial easier to read. To see how the crystal sits among the other external parts, browse the parts category, and weigh up the materials in our sapphire vs mineral crystal guide.
Examples
On everyday dive watches, sapphire crystal is often chosen for its scratch resistance, and the Orient Kamasu follows that approach.
View this watch
Comparison
Sapphire and mineral crystals strike different balances.
| Option A | Option B | Notes |
|---|---|---|
| Sapphire crystal | Mineral glass | Sapphire is the hardest and most scratch resistant but costly; mineral glass scratches more easily, yet it resists shattering and costs less. |
Related terms
Watches that show this
Frequently asked questions
Which crystal type is best for a watch?
There is no single best, it depends on use. Sapphire is the hardest and most scratch resistant but the most expensive; mineral glass is more affordable and resists shattering; acrylic is soft and scratches, though it can be polished out.
What does an anti-reflective coating do?
An anti-reflective coating cuts the glare on the crystal's surface. In bright light you see the dial more clearly instead of reflections bouncing off the glass, which makes the watch easier to read.
Can a scratched watch crystal be fixed?
It depends on the material. Acrylic is soft, so its scratches can be polished out. Sapphire is very hard and resists scratches in the first place, while mineral glass scratches more easily than acrylic.