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Diashock is the name of Seiko Watch Corporations’s proprietary anti-shock system (or shock absorber) for mechanical/automatic watch movements. It was introduced in 1956 in the Seiko Marvel, as part of the brand’s first movement that was fully built from scratch in-house.
“A shock-resistance system that protects the long-term precision.” -Seiko
In technical terms, it is a spring-loaded mounting system for the jewel bearings that support the balance wheel. Anti-shock devices help protect the balance wheel pivot from damage in the event of dropping the watch or hitting it against something hard. In less technical terms you may have heard of Incabloc, Diashock is Seiko’s version of Incabloc.
Two versions of Diashock are the rectangular shaped retainer (two prong) and the three-sided star or clover shaped retainer (three prong). In either case, Seiko refers to their shock absorption system as Diashock.
Not only high end Seikos have Diashock
There is confusion regarding what is and what isn’t considered to be Diashock. Diashock refers to Seiko’s anti-shock system, it is not defined by the shape of this apparatus. Therefore, the three prong star-like retainer is just as much Diashock as the rectangular shaped variation. With that said, modern Grand Seiko watches tend to have the star/clover shaped Diashock.
Diashock in Orient Watches
Although Orient is said to manufacture their own watch movements in their own factories, they are owned by Seiko Epson (since 2009) and use Seiko’s Diashock anti-shock system (as well as magic lever).
Although it would be nice to have a special tool from Seiko for working with Diashock systems, good luck finding it. If it’s your first time installing or removing a Diashock, it may look daunting, but it’s really not that bad. Just make sure it doesn’t propel itself across the room. Watch the videos below showing different ways to work with this anti-shock device. If you do end up finding a Seiko tool, please post pics in the comments below so that the community can see!
Easily setting a Diashock spring in place with pegwood: