Watch Crystals & What They Are Made Of

Watch Crystals & What They Are Made Of

Let’s face it, we cannot have a watch without a crystal. (Actually, maybe there is an exception to that rule.) So let’s say that 99.99% of watches have a crystal to protect the dial and hands, and prevent dust and dirt from getting inside the movement. For the most part, brands use one of three materials for the crystals: plastic, mineral, or sapphire. (There are more types of crystals made of other materials, some being hybrids, however we won’t discuss them today.) While more and more watch enthusiasts advocate for sapphire to be used at all time on any type of watch, they are more expensive to make and therefore to buy. While plastic and mineral crystals are cheaper, more resistant to shocks, but more prone to scratching. As you can see, each one comes with its pros and cons. So, let’s take a look at how each type is made and what would make one better over the other. 

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The Cheapest and Strongest Crystal: Plastic 

Also known as hesalite, plexiglass, and acrylic, plastic crystals have been around for at least 100 years and are the cheapest to manufacture. Crystals of that type are basically made of molded plastic (made of man-made synthetic polymer materials) that is then polished and buffed to look clear. Because it’s molded, plastic crystals can be made in any shape and form, in various thickness, single-domed or double-domed, and they are as easy to replace as they are to make. Their greatest advantage over the other types of crystals is that they have a higher resistance to shocks than, say, sapphire. Instead of splintering, they crack. This is why the first Omega Speedmaster Professionals that joined the Apollo program had plastic crystals as the watches were destined to be banged around the cockpits and against equipment. And that is why many G-Shocks and rugged watches have plastic crystals. But plastic scratches more easily—which horrifies many watch enthusiasts—but in my experience, light and deep scratches can easily be buffed using Polywatch, a cream-based compound made of tiny particles that removes scratches. 

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The Mid-Range Crystal: Mineral 

You may be familiar with mineral crystals as they are widely used on Seiko watches. People often talk about mineral crystals as being the perfect in-between as they are relatively cheap to make and strong. These types of crystals are made of glass (as in window glass,) in other words silica or quartz sand that is heated, shaped, cut and polished to make the material clear and resistant. Which means mineral crystals are strong in the sense that they won’t shatter (either) and are more scratch-resistant than plastic. However, and as far as I know, scratches cannot be buffed on mineral crystals. Generally, it is necessary to replace the crystal when it has been scratched. Since we are speaking of Seiko, it should be noted that the brand developed something called Hardlex, which is also made of glass but manufactured in a way that makes it more resistant to scratches than regular mineral crystals. (I wouldn’t be able to tell you exactly how it’s made.) 

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The Hardest and Most Expensive: Sapphire

Finally, sapphire. While plastic crystals are made of man-made synthetic materials and mineral crystals of melted natural quartz dust, sapphire crystals are primarily made of sapphire (a natural and precious mineral) that is mixed with other naturally occurring minerals which, over a period of several days, are melted together than cooled down several times. This process makes sapphire the hardest mineral on earth and is extremely hard to work and shape, which is why crystals made of sapphire are generally flat (modern iPhone screens are made of sapphire) and that domed sapphire crystals are more rare and/or are much more expensive to manufacture. Sapphire is therefore extremely resistant to scratches, is clearer and glare-free, however it can shatter more easily than plastic and mineral. Generally speaking, watches that come with a domed sapphire crystal could be $100 to $200 cheaper if they were made of plastic. 

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Final Thoughts 

Nowadays, inexpensive fashion watches mainly use plastic or mineral crystals since they are cheaper to make. Luxury brands, on the opposite side of the spectrum, tend to use sapphire because it’s more scratch resistant and is clearer than plastic and mineral. Although I’ve noticed that more and more micro and independent brands now use sapphire. It’s just because watch enthusiasts want scratch-resistant crystals, just like they want ceramic bezel inserts which are also scratch resistant and look more elegant due to the fact that they look shiny. However, sapphire shouldn’t be used on tool watches as it shatters more easily, and instead brands should be using plastic. For some silly reason, many watch enthusiasts look down on good watches equipped with plastic crystals because they don’t look as refined, however plastic is used on many vintage-looking watches because it can easily be molded into hyper-domed crystals and give out a “warmer” feel than sapphire. 

I think by now you’ve gotten my point. Personally, I used to only swear by sapphire but my opinion has changed a lot in the past year. More and more often, I find myself preferring plastic crystals for the reasons I mentioned above, especially on tool watches. But these are just my thoughts. What are yours? 

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