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Types of Watch Glass Explained

Every watch as some sort of transparent covering that protects the dial or digital display underneath. Sometimes referred to as the crystal, this component is also described as the watch glass. There are three different types of watch glass used in the manufacture of nearly every watch on the market. These will be discussed in this guide. Note that some manufacturers have developed their own proprietary watch glass materials. However, they are so brand specific and rare that they will not be discussed in this guide. Needless to say that any modern watch is more likely than not to feature a glass made of acrylic, mineral or sapphire.

Acrylic Watch Glass

Acrylic watch glass is made from a plastic, or polymer, made from acrylate. The plastic is both soft and pliable but still relatively durable. That is what makes it an excellent choice for watch crystals. Its soft and pliable nature allows watchmakers to form it in nearly any shape. Yet the plastic is durable enough to stand up to a significant impact. Popular brands like swatch and flick flak use acrylic glass in their watches.

Watchmakers appreciate acrylic because it is affordable. It can be mass-produced relatively cheaply, thereby not adding significant costs to the watchmaking process. You will find acrylic glass on many low-end and entry-level watches. Acrylic is used less often in manufacturing luxury brands.

In terms of being workable, acrylic can be formed into a variety of shapes. For example, you might have a watch with a domed glass. It is probably acrylic. Creating a dome shape with mineral or sapphire is nearly impossible without spending a fortune. On the other hand, acrylic can be easily formed into a domed crystal without increasing cost. Plastic is a popular choice for watch material and more accurately referred to as Silicon.

 
Pros
In addition to being cheap, affordable and workable, acrylic offers a number of other advantages:
 
Impact Resistance – Because acrylic is flexible, it is also impact resistant. This is a nice feature for dive and sports watches. An acrylic glass should absorb all but the most serious impacts. And even an impact that would damage an acrylic glass will not cause it to shatter.
 
It Can Be Polished – Acrylic can be polished as needed. This is important if your watch get scratched. Although deep scratches are harder to buff out, minor scratches are generally not a problem.
 
Minimal Reflection – Acrylic is a minimally reflective surface, so you are not likely to have trouble reading the dial in bright sunshine. Mineral and sapphire are more difficult to read in the sun because they are more reflective.
 
 
Cons
Acrylic glass does have its disadvantages as well. These are as follows:
 
Low Scratch Resistance – As a plastic, acrylic does not offer a lot by way of scratch resistance. An active person who has trouble avoiding contact between arms and other surfaces might find that an acrylic crystal scratches much too easily.
 
Cloudy Appearance – Over time, acrylic can begin to take on a cloudy appearance. This is true even if a watch is not exposed to extreme conditions. Once an acrylic glass begins to look cloudy, polishing will not help a lot.
 
Cheaper Aesthetic – Some people do not like acrylic glass because they feel it looks cheap. There is no denying that you can tell the difference if you know what you're looking at. You might want to avoid acrylic if you are concerned about its cheaper aesthetic.
 
 

Mineral Watch Glass

Mineral glass is the mid-range product for watch crystals. It costs more than acrylic but not as much as sapphire. For comparative purposes, mineral glass is the same kind of class you probably have in the windows in your home. It is a silica product that offers decent scratch resistance and moderate durability.

Watches in the mid-level price range tend to feature mineral glass. It doesn't look as cheap, for starters. Moreover, it can be hard to tell the difference between a good piece of mineral glass and a piece of sapphire with the naked eye.

 
Pros
Why do watchmakers choose mineral glass? It has some definite advantages:
 
Good Scratch Resistance – Although mineral glass is not as scratch resistant as sapphire, it is certainly more scratch resistant than acrylic. Minor impacts on rough surfaces are less likely to leave scratch marks making this a very durable watch material.
 
Affordable Price – Mineral glass is more expensive to produce than acrylic but less expensive than sapphire. This makes it a good option for mid-range casual wear and designer watches.
 
Pleasing Aesthetic – Mineral glass can be hard to distinguish from sapphire, especially if it has been finished with a thin sapphire layer. Simply put, it does not look as cheap as acrylic.
 
 
 
 
Cons
There are valid reasons you might not want crystal glass as a consumer. These are as follows:
 
Poor Impact Resistance – Of the three glass materials, mineral offers the least resistance against impact. A significant impact to the face of your watch can shatter mineral glass. Cracks are also possible, even when full shattering does not occur.
 
Cannot Be Buffed – Scratches in acrylic can be buffed out. This is not true with mineral glass. Once mineral glass is scratched, it is scratched for good. An excessive number of scratches may require replacing the glass.
 
More Expensive Than Acrylic – For budget minded consumers, acrylic glass may not be doable simply because it is more expensive than acrylic.
 
 

Sapphire Watch Glass

Sapphire is considered the premium material for manufacturing watch crystals. As such, it is also the most expensive. Only your higher-priced watches tend to feature it.

The thing to understand about sapphire glass is that it is man-made. Watchmakers do not use natural sapphire; it is too expensive and difficult to work with. Synthetic sapphire, also known as corundum, is made in a laboratory using a process first developed in the early 1900s. The process creates one of the hardest oxide crystals known to man.

 

Pros

Extreme Scratch Resistance – Being such a hard oxide crystal, sapphire glass is extremely difficult to scratch. You can do it, but it takes an awful lot of effort. It has been suggested that the only thing capable of causing a deep scratch in sapphire is diamond. This makes it an excellent choice for hard-wearing watches for military and luxury watches.

Excellent Impact Resistance – The material's hardness also makes it especially resistant to impact. Under normal circumstances, a typical impact will not bother a sapphire crystal. Saphire will often be combined with a Titanium or other hard-wearing metal like stainless steel strap and body of the watch.

Pleasing Aesthetic – Sapphire's nature as an oxide crystal dictates that it has a very pleasing aesthetic. Kept clean, a sapphire crystal looks stunning. It offers considerably more clarity compared to acrylic. Better yet, it does not get cloudy.

 
Cons

As great as sapphire glass is, it does have some disadvantages. These are as follows:
 
Cannot Be Buffed – In the unlikely event that a sapphire crystal gets scratched, the scratch cannot be buffed out. So just as with mineral glass, a scratch in sapphire is a permanent scratch.
 
Shatter Potential – Impacts do not typically affect sapphire glass. Unfortunately, the rare failures we see with sapphire are catastrophic failures. In other words, an impact hard enough to break sapphire will shatter it.
 
Glare Potential – Because sapphire is so reflective, it is also subject to glare. You may have trouble seeing the time if looking through a sapphire crystal in bright sunshine.
 
Higher Cost – Finally, sapphire is the most expensive of the three watch glass materials. It is expensive to manufacture, expensive to work with, and more expensive at retail. Sapphire class is generally reserved for high-end watches.
 
One final note: there are rare occasions when watchmakers will take a mineral glass crystal and coat it with a thin layer of sapphire. They claim that this coating increases the scratch and impact resistance of the mineral glass underneath. However, such claims have never been scientifically validated. Keep that in mind if you ever encounter a watch with a coated mineral crystal.
 
 

Choosing the Right Option

Choosing a watch glass material really comes down to personal preference. If budget is your primary concern, acrylic is your best bet. You might also prefer acrylic if you subject your watches to extreme punishment. There is no point in damaging a higher-priced watch even if the crystal is better.

In terms of impacts and scratches, ask yourself how frequently your watch comes into contact with other surfaces. If you live and work in a low-impact environment, for example, spending a little more on a mineral or sapphire model might be worth your while. In the end, it boils down to whatever makes the most sense based on your budget and normal use.

 
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