Seiko Mod Sapphire Crystals — Flat & Double Domed, AR Coated

Effectively, yes, for daily wear. Sapphire ranks second only to diamond on the Mohs hardness scale, so keys, desk edges and door frames simply don't leave a mark. Only diamond — or another material approaching its hardness — can scratch it. That's why every crystal we make is sapphire rather than mineral glass.

Flat is the low-profile, original-style look. Double domed curves on both the top and the underside — it catches light differently across the dial and gives the watch a warmer, vintage character. Neither is tougher than the other; both are sapphire. It's a styling call.

It's which faces carry the anti-reflective layers. Single-sided AR is applied to the underside only; double-sided coats both the topside and underside for maximum clarity — noticeably fewer reflections between you and the dial. Every coated face carries at least three AR layers. Some of our crystals also come uncoated, if you prefer the bare sapphire look.

The colour of the reflection, not the clarity. Clear AR is colourless — reflections just disappear. Blue AR kills glare the same way but flashes a subtle blue at an angle, with a slightly brown tint face-on (a standard characteristic of all blue AR). Both do the same optical job; pick the look you prefer.

It's sized for the Seiko 5 SNK family — cases such as the SNK369, SNK789 and SNKL23. The product page carries the full model list, so check yours there before ordering.

The raised profiles: our high top big bevel flats and double domed micro bevels are designed to sit flush with our slope bezel inserts — the crystal edge meets the insert's incline and the two read as one continuous line. It's an aesthetic pairing, not a fitment rule: any crystal with the right diameter fits the case, whichever insert you run.

No — the diameters are different, so they aren't interchangeable. The SKX007 family (7S26-0020, plus SRPD/SRPE) takes a 31.5mm crystal, the SKX013 family (7S26-0030) takes 28mm, and Seiko 5 SNK models take 30mm. Match the crystal to your case and check the Fit Models line in the Specs before ordering.

Yes. A crystal press seats the sapphire straight and evenly — there's no reliable press-free method that doesn't risk cracking the crystal or breaking the water seal. If you don't own a press, a watchmaker or watch-mod specialist can fit it in minutes.

No — the crystal ships on its own, with no gasket in the box. You do need a crystal gasket to install it, but in practice that's already sorted: the crystal seats with the gasket that's in your case, so you simply reuse the existing one. We don't sell gaskets separately because a gasket is cut to match one specific case — ours are cut for Lucius Atelier cases, so a gasket from us would not seal a stock Seiko case correctly. New gaskets come fitted only with our watch cases. If the gasket in your case is hardened, cracked or deformed, replace it with one matched to your case reference — any Seiko parts supplier stocks them.