Choosing The Right Sapphire Crystals for Your Watch

Choosing the Right Sapphire Crystals for Your Watch

Straight from the factory, a typical SKX007 will come equipped with a Hardlex crystal. For a few years, it’ll perform efficiently, then begin to wear and tear. Hence, it’ll only make sense to perform an inevitable sapphire crystal upgrade. Sapphire is a customary SKX Seiko mod that is lush with benefits explained below.

High-Functioning Materials

Sapphire crystals are—literally—tougher than nails. On the Mohs scale, which characterizes the scratch resistance of various materials according to their ability to scratch softer material, sapphire crystals rate a 9. They are the third hardest natural substance in the world, next to diamonds and Moissanite.

With that in mind, note that sapphire crystals in watches aren’t naturally mined. Instead, they are synthetically produced in a lab, enjoying the same benefits as their natural counterparts. Lab manufacturing allows suppliers to avoid having to sell sapphires at prohibitively high prices.

Excellent Form

A scratch-resistant, double-domed sapphire crystal upgrade gives your watch an instant aesthetic boost. There’s no doubt a sapphire crystal will add form and function to your timepiece. From there, it’s all about deciding the type of design that best complements your watch.

  1. Double-Domed Crystal with Beveled Edges

Most aftermarket crystal products are double-domed. As its title suggests, both top and bottom are dome-shaped, reducing distortion on the watch face as you view it from various angles.

Its beautifully chiseled beveled edge is a direct nod to the original Seiko SKX crystal design. It’s incredibly versatile and easy to pair with bezel inserts.

Note that beveled edges tend to collect dust and break the visual flow from crystal to surface.

  1. Double-Domed Crystal with Non-Beveled Edges

Similar to the previous design, it can be challenging to note any subtle differences. However, where the top of the crystal meets the bevel insert, there is close to no gap. If you’re transitioning from crystal to sloped bezel insert, a double-domed crystal with non-beveled edges is your best bet (CT037CIS).

Avoid pairing it with a flat bezel insert—its height will make it look ridiculous! If you’re keen on pursuing a flat bezel, refer to the CT037F design or read up on compatible crystals.

  1. Top Hat Crystal

Named after its tall, rounded silhouette, the Top Hat fits seamlessly into flat inserts. Its edges capture light marvelously, a perfect choice for lovers of vintage, old-timey pieces.

Note: make sure to pay attention to the inside diameter of the bezel insert as the top hat is thicker around its edges. Using ceramic inserts is where you need to watch this the most as they tend to be thicker.

  1. Flat Crystal

A flat crystal looks similar to the OEM SKX007 crystal. It is flat with a beveled edge and is nearly identical to the Hardlex crystal that comes with the Seiko SKX007. If you’re more or less interested in matching your piece to its regular stock, a flat sapphire crystal is hardy and convenient. At certain angles, you’ll even be able to catch the crystal’s stunning AR. We also supply a flat crystal that has no bevel and is flush with the bezel insert “CT025F.”


Sapphire crystals are among every watch enthusiast’s most sought-after Seiko mod part. Durable, purposeful, and modern, a sapphire crystal is always making headlines—and rightfully so! For Seiko sapphire crystal mods that promise impact and strength, SeikoMods offers an expansive collection for those with vintage and contemporary tastes. Whether you’re after a retro design or something a little sleeker, we always have something in store for you (and your wrist).

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