Best Types of Watch Glasses aka Watch Crystals

The first thing you’re looking at in a watch is the watch crystal. A perfect and clean-cut watch glass is a must for easy timekeeping. A watch crystal glass can even reflect a color scheme to make it more gorgeous and pleasant to eyes. 

But what is a watch crystal? Do you confuse it with the quartz crystal in the movement? Watch crystal is absolutely the same as a watch glass. As the molecules are crystallized to produce different types of watch glass, hence the name watch crystals.

Watch crystal is the protective cover on a watch that’s designed to safeguard the watch face and movement from water, impact, or any damages. The harder and stronger the watch glass is, the more durable and long-lasting the watch becomes. That’s why choosing a perfect type of watch glass carries such importance.

But picking a watch crystal can depend on several factors. Your budget, the lifestyle you lead, the watch you choose, the purpose you intended are all can affect your choice for a watch glass. Here we’ve discussed every fact that can help you decide what is the best watch crystal for you. And you’ll also gain wisdom about what is the best crystal for a watch.

Without any further ado, let’s explore the different types of watch glass from plastic to sapphire crystal. After going through this in-depth article, you’ll also find out which types of watch glass suit you the most.

Table of Contents

Acrylic Crystal aka Acrylic Glass

Acrylic watch glass
Plexi acrylic crystal for Tudor

Though widely recognized as glass, Acrylic is actually a type of plastic. The technological term entangles with its historical use as a watch glass. The acrylic glass was the most frequently used cover on the watches. And its classic use in the 80s’ watches still appeals to watch lovers. From Timex to Rolex and Omega use the acrylic crystals on watches.

Though acrylic crystal isn’t a typical silica derivative, it got the historical designation as ‘glass‘ due to the non-crystalline vitreous formation. Acrylic glass is the polymer of methyl methacrylate (PMMA). As it’s a thermoplastic polymer, acrylic is the most flexible and impact-resistant glasses of all.

Acrylic glass is also traded under different pseudonyms. Plexiglass, Acrylite, Perspex, Hesalite are the different forms of Acrylic crystal. They are structurally different but replicates almost the same functionality as the acrylic crystal. Acrylic watch glass is made with the softest material for a watch cover. The thermoplastic polymerization inserts some certain features in it and that’s why acrylic crystals were widely used in the 20th century for a long time.

The soft building material of acrylic watch glass offers the watchmakers to easily manipulate it into any shape. Moreover, acrylic watch crystals are the easiest to manufacture within a very low budget. The watch glass can be manipulated into a dome or flat shape. With the domed angles, the plastic crystal projects a nice distortion. Actually, the domed watch crystal brings the vintage vibes where flat watch glass represents modern freshness. And still, acrylic watches are very affordable.

Acrylic watch crystals can resist any kind of shock or impact. The polymers are connected with weak bonds. The covalent bond allows the watch glass to absorb any kind of shock and distribute proportionally throughout the polymers. That’s why a watch with acrylic crystal can survive a fall or a sudden impact. Acrylic crystals are lighter and more durable than mineral and sapphire crystals. 

But acrylic watch crystals have some serious backlashes for everyday-use. For its softness, the acrylic crystal of a watch can easily get scratched. And it’s the main problem of a watch crystal. Our average life doesn’t need a shock-resistant watch. Rather we need the watches with scratch-resistant glasses. 

And here maybe comes the greatest advantage of acrylic watch crystals. You can easily buff out the small scratches with simple polishing techniques. This way you can reform your old and scratched watch into a new and dashing one. The transparent thermoplastic crystal can easily fix the molecular hassles derived from any scratch and return to its transparent nature.

The crack resistance of acrylic crystal is more than average and it’s highly prone to scratches. Luckily, the small scratches can be removed. And acrylic glass is also slightly prone to corrosive substances.

Uses of Acrylic crystal On A Watch

The playful life of kids needs shatter resistance in watches as they tend to fall and play impactful sports. Kids watches tend to come up with acrylic watch crystals. It’s also used for military purposes. 

The acrylic watches can get scratched but will show time as they’re highly shock absorbent. Practical divers watches also use such kind of acrylic plastic crystal for watches. As acrylic watch glass is highly flexible, the crystal can be easily inserted into hard metal watch cases ensuring water resistance.

How To Identify Acrylic Crystal On A Watch    

How do you tell if a watch crystal is glass or plastic? You can easily identify the acrylic crystal by just having a look. It’s different from mineral and sapphire crystal as acrylic glass is mainly plastic. The cloudy appearance and scratches on the watch crystal are the common sign. 

If you tap on the glass, you’ll get a plastic-like sound. It’s like a blunt and high-intensity sound. If you check the watch glass against your cheek or back of the hand, you’ll feel it hot where mineral and sapphire crystals are comparatively cold.

Mineral Glass aka Mineral Crystal

Mineral Crystal glass for watches
Mineral glass watch crystal

We can term mineral crystal as a second-generation watch glass. Perhaps mineral crystal is the most abundant and common watch glass out there. Perhaps it’s because of a sheaf of mid-range and low-end watches streaming in the market. The mineral crystal projects the bits and bytes of the sapphire luxury only at a handful of bucks. Debuting in the 70s, mineral crystal glass provides a mid-level performance.

Mineral crystal is 100% silica meaning it’s the same glass we use in the windows and other protective luxuryware. But the mineral crystal in a watch is slightly different from the typical one. Mineral crystals are tempered with chemicals and heated at a high temperature. At a very high temperature, the crystallized silica is mixed with the boron. And the process brings forth a hardened surface on the mineral crystal watch glass. And then it’s inserted on watches.

There’s another pseudonym for tempered mineral watch glass. The hardened mineral is also known as ‘hardlex’ crystal. Seiko first introduced this watch glass. And it’s way more protective than the normal mineral glass. It’s in the midway between mineral and sapphire crystal on watches.

Hardened mineral crystal glass can protect your watch from scratches. And it performs way better than acrylic watch glass. Mineral watch glass is also more than average resistant to cracks or shatters. But the performance isn’t even close to the sapphire crystal. 

On another note, acrylic crystal is more durable and easy to use than the mineral watch crystals. Once scratched, you can’t revive the lost glory of the mineral crystals glass. But acrylic crystals can be revitalized from multiple scratches through proper polishing methods. 

Mineral crystal or Hardlex watch glass is very functional for entry-level watches. If beauty is your preference and budget is the restraint, then you can go for mineral crystals on watches. Mineral crystal is comparatively corrosive resistant than acrylic glasses. It can withstand hard water while acrylic glass can only endure normal water. Mineral Crystal also has a higher resistance to dangerous substances like acids and bases.

Mineral glass can still crack or shatter if you leave your watches at an extremely high or a cold temperature. But your daily lifestyle won’t impress any scratches on the watch glass that easily. The angles sometimes filter and project specific rays that intensify the beauty. But it’s more reflective than the acrylic watch glass. However, mineral crystal glass is less light-reflective than the sapphire crystal on watches. Because sapphire watch crystals have a higher index of refraction than mineral watch glass.

Uses Of Mineral Crystal On Watches

Mineral crystal is the most common glass for entry-level watches. Perhaps you have a mineral crystal on your watches but you didn’t notice. Low-end watches have such mineral crystals. You can also find mineral crystals covering high-end movements. Even Omega has some models with mineral glasses. It’s also used on fashion watches as the mineral crystal is relatively cheap to buy. If sapphire crystal on watches is out of your budget, you can try the entry-level mineral crystal glasses.

How To Identify Mineral Crystal On Watches

Mineral crystal is more transparent and clearer than acrylic glasses. You can easily identify the difference between mineral crystal vs acrylic crystal. Mineral crystals have fewer scratches and they reflect blue accents from angles.

However, it’s tough to differentiate mineral crystals from sapphire crystal glass due to their outward similarity. So the experts test 2 types of checking to ensure credibility. If not done in the watch store unto your request, you can try it home.

The sound test includes tapping on the mineral watch crystals with your fingernails. If the sound is high-pitched and loud, then it’s mineral crystal. Otherwise, it’s a sapphire watch crystal. 

You can also test it with a drop of water. Upon the dropping of water, if it diverges throughout the glass, it’s the mineral crystal. If it stays as a drop, the crystal is a sapphire watch glass. It’s an effective and easy procedure to distinguish different types of watch glass.

Sapphire Crystal aka Sapphire Watch Glass

Sapphire crystal on watches
Sapphire crystal

Sapphire crystals in watches are the latest edition in the watch glass chemistry. It surpasses the mineral and acrylic crystals from all aspects. The all-round performance takes it into the higher ground. But the prevalence of sapphire crystal on watches in the 90s makes it affordable since now, despite the manufacturing cost and performance. Surely sapphire crystal is the best pick to protect your luxurious and lovely timepiece.

It’s indisputable that sapphire is the hardest and toughest natural substance after diamonds. But it’s not natural sapphire that’s used in watches. Rather the watchmakers use synthetic sapphire that’s produced in the laboratory. Synthetic sapphire is totally similar to the natural sapphire gemstone in regards to hardness. The only difference is the absence of hue in synthetic sapphire that is carefully avoided during the production.

Synthetic sapphire crystal scored around 9 in the Mohs scale of hardness test. Here diamond is the parameter because diamond has the highest Mohs score of 10. That’s why manufacturing cost increases for producing sapphire crystals in watches. Because no other equipment other than the diamond-coated saw can cut and prepare the sapphire crystals.

Sapphire crystal for watches is prepared by crystallizing Aluminum Oxide (Al2O3) at a high temperature. To contain its rigidity some other elements are also added e.g. magnesium, copper, iron, titanium, etc. The expensive tools and need for delicate drilling and milling of sapphire crystal highers the budget for manufacturing. The addition of anti-reflective coating is another area to increase the cost. To sum it up, sapphire crystal glass costs higher than mineral and acrylic watch glasses.

Synthetic sapphire is a trustworthy protector of watches since they are extremely effective against any kind of scratches or impacts. You can try it using your knives on the sapphire crystal. It’ll barely leave any scratches. However, the outer AR coating can be scratched. And if you’re not planning to fall it in a ceremony or use it for military purposes, the sapphire crystal will remain as new as before. It can easily withstand any conflict or a door jam. The absolute clarity and transparency of the sapphire crystal are worthy of buying.

But sapphire crystal is still susceptible to damages. A heavy impact can shatter and break the watch crystal into pieces. As it’s not flexible as acrylic glass, the fragile chemical bond of sapphire crystal will easily fall down. Sapphire crystal can show the ultimate scratch resistance but not the shock resistance. Another plus point is the resistance of sapphire crystal towards any corrosive substances. Even a moderate amount of acids and bases can’t put any scratches on the crystals.

Though it’s believed that sapphire crystals can only be scratched by diamonds and sapphire, several man-made materials can cause damages. Silicon Carbide has a hardness score of 9-9.5 on the Mohs scale. It means anything with silicon carbide can scratch your sapphire watch crystal. Silicon Carbide is used to produce the hardest ceramics. And it’s also used in electronics equipment. So you may not want to collide with any of these products containing the silicon carbide also.

However, sapphire crystals have evolved into various shapes and designs. The prominent varieties of sapphire crystals on watches are the

  • Flat shaped sapphire crystal
  • Dome-shaped sapphire crystal

Though dome-shaped sapphire crystal projects a vintage style while modern style lies at the exhibition of flat crystal windows. Dome shaped crystals are regarded as stronger than the basic flat design. Because domed sapphire watch glass has a larger surface area that distributes the impact in a larger area and reduces the risk of shattering. However, the domed surface may cause distortion as light reflection may hamper timekeeping from angles.

The AR coating or anti-reflective coating is a necessary installment in the sapphire glass in watches. Due to the higher refractive index, sapphire crystal reflects more light than mineral crystals. There can be one or two layers of AR coating both inside and outside of the sapphire crystal. The outer coating tends to wear and tear in the long run and leaves something like scratches. You can choose only the inner coating if you prefer.

Uses Of Sapphire Crystal On Watches

Sapphire crystal is the epitome of luxury as it mostly associates with high-end timepieces. But nowadays sapphire crystal is found in abundance on entry-level watches for its relatively low cost. However, all brands don’t provide the same sapphire crystals with the same endurance to cracking and shattering. If you’re up for a premium watch, you’ll get it no matter what.

How To Identify Sapphire Crystal On Watches

How can you tell if a watch is a sapphire crystal? Sapphire crystal is easily distinguishable from acrylic glasses. It’s absolutely clear and transparent. You can also identify sapphire crystals checking some distinct features. As the physical appearance of mineral and sapphire crystals can be confusing, you can use sound or water drop methods.

If you tap on the sapphire crystal glass, you’ll hear a solid and low-pitched sound. It’s different from the mineral crystal as the tapping sound is sharp in a mineral watch glass. Also, if you use a drop of water in the sapphire crystal surface, the water drop will stay put and won’t diverge like in the mineral glass. Thus you can easily distinguish different types of watch glass.

Other Types of Watch Crystal

There are several other types of watch crystal that are treated and manipulated from the common types of watch glass. Different brands produce their own types of watch crystals that score differently on the Mohs hardness scale. Adorned with different brand names, the watch crystals are gaining popularity these days.

K1 Crystal aka K1 Mineral Crystal

K1 glass is another branded watch glass produced mainly by luxury watch brand, Movado. Same as the Hardlex crystal by Seiko, Movado started the quest to provide a space-age technology to protect watch movement. 

Actually, K1 crystal is a treated mineral glass that’s more scratch-resistant than the regular mineral crystal and way more shatter-resistant than sapphire crystal on watches. K1 is the symbol of purity and clarity and it makes the watch more protective. The watch with K1 crystal can take the toll of your rugged lifestyle for a lifetime. K1 mineral crystal is really an extra-ordinary addition in the watch industry revitalized by the Movado watch brand.

Krysterna Watch Crystal

Krysterna crystal is another trademark product of Stührling and its subsidiary brand named Akribos. Though little is known about the materials used in krysterna watch crystal, we can’t define the quality by checking its high price point. Krysterna crystal is used in the luxury watches of the Stührling brand.

Stührling claims krysterna crystal to be the most effective watch glass in the market. Though different types of watch glass of different brands claim such things, it may not be the marketing hype of these brands. As we see krysterna crystal is more shatter resistant than the sapphire crystal. Sapphire crystal is very poor at shock resistance for its ultimate rigidity. However, krysterna crystals are more scratch-resistant than mineral crystals. It can be termed as the same different types of watch crystal-like Hardlex or K1 glasses.

Sapphlex Watch Glass

Sapphlex crystal is another type of watch glass that’s claimed to be the best of the Hardlex and sapphire crystals. From the name, you can catch the game of this sapphlex watch glass. It’s the hybrid of hardlex crystal and sapphire crystal. And first introduced by Seiko, sapphlex is claimed to adopt the best quality of both hardlex and sapphire glass. 

Sapphlex is actually a mineral crystal that’s coated with sapphire crystal on its surface. It has the potential of sapphire crystal in scratch resistance as well as the shatter resistance of mineral watch crystal. Though it was marketed as a cost-effective alternative to sapphire crystal, the production is decreased due to the lowering manufacturing cost of sapphire glass. 

Acrylic Crystal vs Mineral Crystal vs Sapphire Crystal

Acrylic vs Mineral vs Sapphire Crystal
Acrylic vs Mineral vs Sapphire Crystals

These are the major types of watch glass prevalent in the market. Let’s have them boxed in a corner and discuss the differences among acrylic vs mineral vs sapphire crystals on watches.

Scratch Resistance

Sapphire crystal is the best choice for scratch resistance. As shown earlier, only diamond, sapphire, and pure ceramic can scratch on its surface. Mineral crystal has lower resistance to scratches than sapphire crystal but more effective than acrylic crystal. That leaves acrylic crystal to be the most susceptible to scratches among all types of watch glasses.

Shatter Resistance

In the case of shatter resistance, acrylic crystal can be your best choice. Acrylic crystal can break but doesn’t shatter into pieces. Even Rolex and Omega used acrylic crystals on their watches. The Speedmaster that went to the moon adorned acrylic crystal glass to avoid any cracks or breakage. Moreover, acrylic crystal is very cheap to buy and easily manageable.

Mineral crystal is 7 times harder than the acrylic watch crystal. But mineral crystal also shatters in an extreme condition as mentioned earlier. Sapphire crystal is an ultimate boss to manage scratch resistance but it can also shatter if heavy impact is applied.

Cost Effectiveness

Acrylic crystal is the cheapest of all types of watch glasses in the market. Easy manufacturing and cheap materials are the main reasons for its affordable price tag. If damaged, you can easily change the acrylic crystal by spending a little buck. 

However, mineral crystal is relatively more expensive than acrylic crystal. But it’s also at the reach of the average Joes. Sapphire crystal is the most expensive watch crystal. It’s seen in the luxurious and high-end watches. However, the price isn’t significantly higher and it differs from brand to brand.

My Preference among Different Types of Watch Glass

I personally don’t fall for the hype. I rather play the emotion behind a thing! Acrylic crystal isn’t so bad though it sounds cheaper as people tend to say it. If you’re on a budget, an acrylic crystal will do more good than other types of watch glass. You can switch acrylic glasses whenever you want. The scratches can be polished anytime reviving the new look. And acrylic crystal doesn’t shatter. So what more do you want on such a budget.

But if you can afford sapphire crystal you should take the chance. The transparency and clarity are beyond any dispute. The gorgeous angular distortion seems exceptional to me (can’t diagnose the fact). However, sapphire crystal can last for your lifetime without any scratches. And we don’t need more shatter resistance than we need scratch resistance. So a sapphire crystal on watches can captivate you for years ahead with its eye-catching performance.

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