What Is A Sapphire Crystal? Everything You Need To Know

If you’ve ever wondered what a sapphire crystal is or why it’s such a gold standard, here’s everything you need to know.

A friend of mine recently inherited a vintage Omega outfitted with a mineral crystal. Without skipping a beat, he immediately mentioned he’d likely “upgrade” it with a sapphire. 

Of course, I had to do my watch guy thing and mention that it could compromise its originality. Changing a vintage watch’s crystal is akin to putting modern rims on a vintage car.

Even though sapphire dials are renowned, Seiko watches tend to use their in-house Hardlex, even at price points at which other brands would utilize sapphire.

This begs two questions — what exactly is a sapphire crystal in a watch and is it actually better than the alternatives?

Today, I’m going to tell you all about the coveted sapphire crystal glass.

Advantages of Sapphire Crystal on Watches

Dial protectors on a watch can be built from mineral crystals, acrylic crystals, or sapphire. A sapphire dial protector is produced in a lab, a ceramic material created when powdered aluminum oxide is heated and placed under intense pressure.

A French chemist, Auguste Verneuil, invented this process. The result is a strong and beautiful glass that’s essentially scratch-resistant and cool to the touch. 

In fact, on the Mohs hardness scale, sapphire scores a 9. Examples of materials with a score of 10 include moissanite and diamonds.

This means that it would take a diamond to scratch your watch’s sapphire glass. The crystals’ incredible scratch-resistance are why they’re considered the most premium option when it comes to protecting your watch face.

By the way, to learn more about other watch crystals, including acrylic and mineral glass, check out our guide to dial protectors.

Disadvantages of Sapphire Crystal

We’re constantly told about all of the advantages of sapphire crystal, but are there any drawbacks? Technically, yes. But in practice, no.

First off, one disadvantage of sapphire is that it’s expensive. But hey, you pay for quality. Sometimes, brands will take a mineral crystal and give it a thin sapphire coating.

It’s less expensive and fairly scratch-resistant, though, of course, it isn’t as strong as full sapphire.

Another disadvantage is that sapphires aren’t perfectly shatter-proof. In fact, it used to be a requirement for military watches to have acrylic or mineral glasses because of this. As you can imagine, in the trenches, scratches are better than shatters.

However, most of us won’t engage in activity with such a high level of impact that we’d ever shatter the sapphire of a high-end wristwatch.

And finally, sapphires aren’t naturally that clear. They have a fairly strong light refraction, which is beautiful but can result in reflections.

Still, most watchmakers will put an anti-reflective treatment on the glass, making this a moot point. The more layers of AR coating, the clearer the watch will be, especially if it’s on both sides of the protector.

Brands That Use Sapphire Glass

Basically, every high-end Swiss brand outfits their watches with sapphire glass.

Truly, any line of watches that has a premium subline will most likely use sapphire glass over the alternatives. It’s a sign of high-end status when it comes to contemporary watches. 

That’s why so many brands that utilize sapphire-coated minerals will often use language that sounds like they might be using actual sapphire. Watch out for brands that try to mislead you this way. 

So yes, Rolex, Patek Philippe, and Audemars Piguet all use sapphires on their modern models. Although they’ve been used since the ‘30s, ever since Rolex put a sapphire on their 1970 Reference 5100, it became the standard for premium timepieces.

Rolex even has a special green sapphire that they use for their Milgauss line. The funny thing is that natural sapphire gems can be yellow, purple, green, or even red, depending on what other materials they’re combined with.

Pure sapphire gems are actually quite rare, which is what makes them desirable in jewelry.

FAQs

Here’s what people are asking on the web about sapphire: 

How Can I Tell if My Watch Has Sapphire Crystal?

Touch the surface. If it’s cool to the touch, it’s likely sapphire. You can also place a drop of water on the surface of the glass. If it remains a spherical drop, it’s sapphire. If it spreads out, it’s mineral or acrylic.

Is Sapphire Crystal Good for Watches?

Yes, sapphire crystal has several advantages. For example, it is one of the hardest substances, with a score of 9 on the Mohs hardness scale, while a diamond has a score of 10.

Sapphire provides excellent protection for your watch dial, which is why it’s more expensive than other dial protectors.

What Does a Sapphire Crystal Do in a Watch?

Sapphire provides premium protection. It’s scratch-resistant and attractive, and it ensures a longer life for your watch.

Most sapphires feature anti-reflective treatment too. With all of these advantages of sapphire crystals, you’ll have top-notch legibility for decades to come.

Conclusion: The Sapphire Standard

So basically, the only real downside to sapphire is that it’s not the most transparent material compared to other dial protectors.

But again, AR treatment will fix that right up. These days, if a watchmaker is going to bother outfitting a watch with a sapphire, they’re certainly going to ensure its clarity.

Overall, the sapphire crystal has become the top standard in watchmaking because its strengths and aesthetic are more applicable to life today. No one wants a scratched-up watch glass.

And sure, you might want to keep a vintage brand-name timepiece as authentic as possible, with most of its original parts.

When it comes to an old non-investment watch that you love or has sentimental value, perhaps you’ll want a stronger protector.

Do you think sapphire crystals are worth it? And have you ever upgraded an old watch with one? Let me know!