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Sapphire vs Mineral vs Acrylic Crystal vs Krysterna

October 11, 2021

Forget Alice in Wonderland. It’s time to step through the looking glass and discover which watch glass will suit your discerning needs.

Wristwatches come in all shapes and sizes. Something that remains the same, though, is the glass form giving protection to your precious dial. Yet questions are thrown up that will make your head spin as much as that second or minute hand.

What’s the best watch glass and what are the main differences between each material? How is each glass type defined?

Fret not watch fiends. Utilizing my horological experience, I will guide you through what to watch out for! We're here to give you the lowdown on the key differences between each material. So which is a cut above the rest?

Sapphire Crystal

The weapon of choice for premium watches, Sapphire is considered the Rolls Royce of watch materials. As tough as Anthony Joshua bench pressing The Hulk, this man-made product isn’t actually glass per se but rather synthetic.

Known as Aluminium Oxide, it is the costliest on the market. As for scratch resistance? Extremely high! You’ll be hard-pressed damaging a domed or flat sapphire crystal watch aside from cutting it with another diamond.

When timepieces are exposed to harsher conditions such as during battle or in the Air Force, there are better options available such as acrylic. How about shatter resistance? We give this a moderate rating. Why? It’s down to the brittleness of sapphire. Prone to cracking the result will be a sorry sapphire mess into numerous pieces.

Concerning transparency, it’s exceptionally crystal clear offering an anti-reflective coating with plenty of luminosity through the dial. But hold the phone...there’s another type of sapphire out there called sapphire mineral crystal.

Fast becoming de rigeur with microbrands it combines sapphire laminate on top with a mineral glass layer. Although it’s more prone to scratches it can withstand greater impacts Several brands have already utilized this technique including Seiko.

Businessman checking the time

Mineral Crystal

If your wallet doesn’t stretch to high-end Sapphire, the mineral may be an alternative. Featured in a variety of entry-level watches, it is not as scratch-resistant as its sophisticated sister Sapphire.

You will also find “Hardlex” in this specific category. Developed by Seiko, it benefits from similar properties to mineral glass. Like acrylic, it has far greater protection against knocks, scratches, and scrapes.

And where can you find mineral crystals? In the majority of low-end fashion design watches given its cheap production costs. Sadly, its anti-reflective properties aren’t as great when compared to Sapphire.

Plus, damage can be costly (literally!) If the face is cracked or chipped, repairs are almost nigh on impossible to conduct. Now that’s one big impact.

Acrylic Crystal

For telling the time, this material, or to give its proper title polymethyl methacrylate, can be shaped to fit a dial. With its relatively low cost, this is the most price-friendly alternative while the scratch resistance doesn’t hold up either.

The majority of cheap watches will normally house acrylic crystal or vintage and retro watches. This gives it a distorted appearance when viewing at an angle. It does have the feel of cheapness among many watch aficionados as the material can lead to frequent scratches.

Meanwhile, thanks to the crystal’s flexibility, impacts also score highly on the resistance scale. In fact, acrylic crystal watches are almost unbreakable. Although acrylic can scratch, you would need the strength of a rugby team to break this baby to bits.

There is a moderate transparency rating with partial dial cloudiness occurring over a period. The transparency through the watch face is quite low but there are some nice refractive effects when turned on its side.

Brimming with character, if you’re searching for a cost-effective, robust face that can hold up to pretty much anything, acrylic should be your go-to material.

Omega Seamaster Planet Ocean

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One of the most unusual materials out there is Krysterna.

Manufactured for Stührling watches, this rare watch glass appears to be used by its sister brand Akribos. What little details we have proves to be fascinating reading. This brand claims Krysterna is the finest material for dials outperforming Sapphire in shatter resistance.

We beg to differ as sapphire is certainly known not to be earth-shattering in these stakes but holds more credibility and toughness than Krysterna. This does raise questions immediately about its credibility. Similar to Hardflex, all we can say is it seems to be some sort of mineral with proprietary or toughened mineral crystal coating.

According to their official site;

“Our Krysterna crystal process takes ultra-pure (99.9995% and above) aloxite and bombards it with oxygen and hydrogen, then heats the aloxite to 3630 degrees Fahrenheit to liquefy it into droplets. When those droplets harden, they transform into a crystal clear material that’s more durable than mineral glass and the countless acrylics used by other manufacturers."

So, what have learned from this definitive guide?

We know Sapphire is the top material used in luxury timepieces offering first clarity but less shatter resistance. For price-conscious folk, mineral crystal is ideal for sustaining more bumps and knocks than Tyson Fury.

And with excellent flexibility, acrylic crystal is great for vintage watch fiends. Krysterna provides a one-of-a-kind alternative material only found in the German brand Stührling but the jury remains out on its credibility.

Numerous mixed reviews within the watch community mean only time will tell whether they are dialed in for success.

Simon Lazarus
As an avid watch fiend, Simon Lazarus isn’t any ordinary watch collector. Since the dawn of time (well almost), his obsession with timepieces has seen him establish a bijou collection across his extensive travels with his wife and two darling daughters including in the US and Dubai. With an extensive back catalogue of published work on timepieces for numerous sites globally, watches are moments in history. He certainly makes time to capture the true essence of watchmaking with an eye for impeccable detail showcased in his plethora of watch articles across numerous sites. With a well formed selection focusing on Swiss made as well as emerging microbrands that will no doubt gain in value, time is almost as precious as his two young princesses!
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