The Different Types of Watch Crystals: A Guide

Watches are made up of smaller components that serve a greater purpose when assembled. Some of the well-known watch parts include the bezel, case, and crystal. The crystal is fundamental since it’s what allows us to view the time indicated on a watch. 

Most watches have crystals attached to them, with the sole exception of watches made for blind people. Today, different materials are used to create watch crystals. These include acrylic (plastic), mineral, K1, and sapphire crystals.

Why are there many materials used in making watch crystals? Do they have significant advantages and disadvantages over one another? This article sheds some light on watch crystals. Read on below to learn more.

A History Lesson

It’s hard to imagine a watch without a crystal, but it used to be a real thing. Watches did not have crystals on them until 1610, which is when waistcoats with pockets were introduced. These waistcoats with pockets were Charles II’s primary outfit of choice. 

Watchmakers also wanted to make use of these pockets, and soon enough, the first pocket watch was made. It was fitted with glass later on to prevent damage to the face of the timepiece.

Types of Watch Crystals

Now that you know the background of watch crystals, it’s time that you know more about their different types.

  • Acrylic Crystal

Also known as plexiglass crystal, it was first produced in 1928. It wasn’t until five years later that acrylic crystals became commonplace. Despite being softer than the other materials listed below, acrylic crystals are shatter-resistant. 

They were first used on military watches in World War II because soldiers were required to wear watches with non-breakable crystals. As time went on, acrylic crystals became obsolete. While you can still find watches with acrylic crystals today, they’re often associated with older, vintage designs.

Pros: Shatter-resistant, cheaper, lightweight, and has vintage appeal

Cons: Prone to scratches and has low clarity

  • Mineral Crystal

When acrylic crystals became a thing of the past, the market demanded a new watch crystal. This gave rise to mineral glass. True enough, tempered mineral crystals improved on every aspect of the acrylic crystal.

Pros: More durable, has significant resistance to scratches and corrosion, and better clarity

Cons: More expensive and can also crack or shatter under extreme conditions

  • K1 Crystal

Like its predecessor, the needs of the market weren’t met by mineral crystals. Companies then thought of an alternative way to get the results they wanted by producing crystals that mixed a mineral crystal’s scratch-resistance with an acrylic glass’ durability—creating the K1 crystal. The K1 crystal is a heat-treated mineral glass that combines the best of both worlds.

Pros: Improved scratch and shatter resistance, super durable, and better shatter resistance

Cons: It can still break if it falls or gets hit, and scratches are still possible despite low chances

  • Sapphire Crystal

The sapphire crystal was introduced in the 60s. It may be called “sapphire,” but it’s not made from genuine sapphire—it’s made from a synthetic material that uses pure aluminium oxide. Natural sapphires were used in the 1920s, but the artificial process allowed watches to have crystals without defects found in genuine sapphires. 

Sapphire crystals are also far superior to any of the other crystals mentioned in this article. For any high-end luxury brand, sapphire crystal is their primary choice when producing watches.

Pros: The hardest crystal and highest level of scratch resistance and clarity, and is also corrosion-resistant

Cons: Expensive, and it’s also prone to cracks and shattering


The clear winner among crystals is the sapphire crystal because it’s better than all of them. However, it’s still important to note that different crystals are still available today, which attests to the fact that they still have their uses even if there are lesser kinds of crystals. In the end, you’ll want to invest in one that best suits your preferences. 

Watch crystals are entirely changeable, which means that you can get a better crystal for your watch. Seiko Mods offers Seiko mod parts that can be the next best thing for your watch. You should always get the best components possible so that you can get the most out of your watch. Order yours to get started!

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