Watch crystals are an important part of every watch. Crystals provide protection and subtly add to the look and feel of watches.

Keep reading to learn a bit more about the history of crystals, what they are, the materials used to make them, and more.

To learn more about the various parts that make a watch, visit our blog on the 17 main parts of a watch.

Mineral watch crystal and skeleton dial of the Nixon Spectra automatic watch

What are Watch Crystals?

A watch crystal is the piece of glass or acrylic that protects the watch dial from shock, dust and moisture damage. Watch crystals come in a variety of materials including acrylic, mineral glass and sapphire.

A Brief History of Watch Crystals

Unlike modern wristwatches and clocks, the earliest clocks did not use crystals for protection. Instead, many had open, exposed faces. Later, hinged metal was added and could be opened to read the time, or closed to protect the face of the clock.

Sometime in the 17th century, "rock crystal", a form of quartz, was introduced into watch making. This is where watch crystals get their name.

In the 19th and 20th centuries, new materials, like synthetic sapphire and acrylic, began to appear in watchmaking as protective watch crystals.

3 Main Types of Watch Crystal

Today, the majority of watches use one of three different types of material for the crystal, as mentioned above.

Here are the three types of watch crystal, in order of least expensive to most expensive.

Acrylic Crystals

Acrylic crystals are created from a plastic compound. They are common in watches because they are inexpensive, easy to replace and shatter resistant.

Here are the pros and cons to know about acrylic watch crystals:

Low cost Easily scratched
Easy to replace Light reflection
Shatter resistant

Mineral Crystals

Mineral glass crystals are also common in watches. This type of crystal involves the treatment of ordinary glass for the purpose of preventing the glass from splintering in the event of a breakage.

Hardened mineral is the most common type of watch crystal on Nixon watches.

Here are the pros and cons to mineral glass watch crystals:

Medium cost Hard to remove scratches
Good shatter resistance
Good scratch resistance
Less light reflection

Sapphire Crystals

Synthetic sapphire used in this type of watch crystal is nearly as hard as a diamond. That makes this crystal type extremely scratch resistant.

Check out the pros and cons of sapphire watch crystals:

Very little light reflection High cost
Extremely scratch resistant Impossible to polish scratches
Low shatter resistance

How to Tell the Difference in Watch Crystals

If you are unsure what type of crystal your watch uses, finding out is fairly easy.

The easiest type of crystal to identify is acrylic. If your watch crystal appears to be made out of a hard plastic-like material, it's almost certainly acrylic.

Mineral and sapphire watch crystals are much more difficult to identify with just an eye test. Here are two ways you can test your crystal to learn if it's sapphire or mineral:

  1. Water Test: Using a dropper or some other way to form a water droplet, drop water on the watch crystal. If the water droplet flows and spreads, you have a mineral crystal. If the droplet maintains its shape, you have a sapphire crystal.
  2. Sound Test: Gently tap your fingernail on the crystal and pay close attention to the sound it makes. If the sound is high-pitched, you have a mineral crystal. If the sound is lower and solid sounding, you have a sapphire crystal.