Types of Watch Glasses : A Beginner’s Guide

Watches are not only functional timepieces but also stylish accessories. When shopping for a watch, it’s important to consider the design, durability, and overall look and feel of the watch. One crucial component that affects these factors is the watch glass. Different types of watch glasses have different properties and can affect the watch’s appearance, scratch resistance, and water resistance. In this beginner’s guide, we’ll take a look at the most common types of watch glasses and their characteristics, so you can choose the best option for your needs.

Note: The terms “watch crystal” or “watch glass” refer to the transparent glass material that covers and protects the dial of the watch.

Generally, there are three types of watch glasses used in watches.

  1. Acrylic Watch Glass
  2. Mineral Watch Glass
  3. Sapphire Watch Glass

1. Acrylic Watch Glass

Acrylic glass, plexiglass, and hexalite are all names for the same material called Polymethyl methacrylate (PMMA). Acrylic glass is a thermoplastic and is the least expensive type of watch crystal. Because it is less expensive to manufacture than mineral or sapphire, low-cost watch brands usually use acrylic glass in their watches. It is commonly seen in entry-level, low-end, and children’s watches. 

Acrylic watch crystal is rated three out of ten on the Mohs Scale (which measures the hardness and scratch resistance of minerals). Because of its softness, it is easily scratched. However, minor scratches may be buffed out. It can also be molded into any shape. Mostly the acrylic watch glass comes with a dome shape.

It is suitable for sports, dive, and military watches since it can withstand a heavy impact.


  • It is inexpensive and has minimal manufacturing costs as compared to mineral and sapphire glasses.
  • Because of its flexibility It is highly resistant to impact. You don’t have to be concerned about it being damaged or shattered.
  • In the case of damage, you can easily replace it.
  • Minor scratches can be rubbed out.
  • It is lighter than mineral and sapphire glasses.


  • The main downside is that it is made of plastic, which scratches easily. However, minor scratches can be buffed out, but in the case of major scratches, you have to replace it with a new one.

2. Mineral Watch Glass

Mineral glass is frequently used in watches and is considered the most popular type of watch glass. It is sometimes called “hardlex,” although there is a little difference between the two, which I will discuss later in this article. Mineral glass is similar to regular glass found in everyday items like windows and picture frames.

Watch Crystal

The Mohs Scale gives mineral glass a rating of 5 out of 10. When compared to acrylic crystal, it has a higher scratch resistance. It can remain clean and clear for a long time if properly cared for. 


  • It is also as cheap to produce as acrylic glass, however it is somewhat more expensive to manufacture but still affordable.
  • It has more scratch resistance than acrylic glass.
  • Surface level scratches can be buffed out.


  • It is more easily destroyed than acrylic glass and cannot resist a severe impact.
  • It does not have the same level of shadow resistance as sapphire glass. 

Note: Some watch makers provide a mineral crystal with an AR (Anti Reflective) coating to reduce light reflection in front of the watch glass . It improves the visibility of the watch dial and makes it easier to read the watch in high-light conditions.

3. Hardlex Watch Crystal 

Hardlex crystal is a type of tempered mineral glass that is commonly used in watches. It is a proprietary material developed by Seiko, a Japanese watch manufacturer, and is known for its excellent durability and impact resistance. Hardlex crystal is formed by heating a mineral glass and then rapidly cooling it, resulting in a material that is much harder than regular mineral glass. This makes it highly resistant to scratches and impacts, making it a popular choice for sports and diving watches. Although not as scratch-resistant as sapphire crystal, Hardlex crystal is still a highly reliable and affordable choice for watch enthusiasts.

4. Sapphire Watch Glass

The sapphire glass is the most expensive of all watch glasses. It is mostly utilized in high-end and expensive watches.

A Seiko Watch With Sapphire Crystal
Seiko Watch With Sapphire Crystal

Sapphire crystal is the third hardest mineral on the Mohs scale with a 9 rating, after diamond (which has a Mohs rating of 10) and moissanite (which has a rating of 9.5). So you shouldn’t be concerned about it getting scratched because it can only be scratched by materials with hardness greater than it. 

I’d like to share with you a fact: in most cases, watchmakers use synthetic sapphire created in a laboratory rather than natural sapphire in their watches. The reason for this is that natural sapphire is much more expensive than synthetic sapphire, but don’t worry because synthetic sapphire has practically all of the same properties as natural sapphire. In 1911, French chemist Auguste Verneuil patented the process of creating synthetic blue sapphire. 

The sapphire watch glass has the most scratch resistance, but it also has the least impact resistance. Unfortunately, it cannot endure a heavy impact and is quickly shattered.


  • When compared to mineral and acrylic crystals, it offers the highest scratch resistance.
  • It has a pretty much shadow resistance so you can easily see the dial.
  • It provides the watch a high-end appearance.


  • It is more expensive than acrylic and mineral glasses
  • Although it can handle normal hits, it cannot resist heavy impacts.

How Do You Know What Kind Of Watch Glass You Have?

If you buy a watch glass from a well-known store or a trusted brand, obviously you won’t have to identify which one you’re getting because they’ll inform you if it’s acrylic, sapphire, or mineral.

However, if you have to buy it from a local store or an unknown brand, you must understand how to ensure that you are receiving the correct glass.

Here are some tips from experts on how to identify and differentiate between these three glasses.

The simplest technique to determine whether the glass is acrylic is to place it against your cheek. Acrylic is generally warmer than the other two (mineral or sapphire) crystals.

You can distinguish between mineral and sapphire by putting water drops on the glass. If the drop remains in its original shape, it is most probably Sapphire; if it expands, it is Mineral. 

Which Type of Watch Glass is Best For You?

The simple answer is it depends on your preferences and needs, as well as your lifestyle and usage. For everyday wear such as in the workplace, mineral crystal may suffice. However, for those with busy and active lifestyles where there is a greater risk of the watch crystal breaking, acrylic glass with its high impact resistance is recommended. For special occasions, sapphire glass is the ideal choice.

When it comes to cost, acrylic is the most budget-friendly option among the three. Ultimately, the choice of which type of watch glass to go for depends on your individual circumstances and lifestyle.


In conclusion, choosing the right type of watch glass is an important aspect of selecting a watch that meets your needs and preferences. Acrylic, mineral, sapphire, and other specialty glasses all offer unique properties that affect the watch’s durability, scratch resistance, and overall appearance. By understanding the differences between these types of watch glasses, you can make an informed decision and ensure that you choose a watch that meets your expectations and lasts for years to come.

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