Recently purchased a '65 Crosshair Seamaster 166.003 with a cal. 562 that had pressure cracks in the crystal. https://omegaforums.net/threads/arrivals-what-did-you-buy-recently-watches.8930/page-709#post-1541788.
I figured they were just scratches when I bought the watch that could be buffed out, but the marks were inside the crystal. I was not aware that this kind of crystal damage was possible. Is it common? Other than the obvious answer 'pressure,' what causes this? Is it a breakdown of the crystal over time? Definitely something to watch for in the future. I'd appreciate any insight you may have on this type of damage.


Nice accumulation. May be the first time the bezel was off.

New crystal and a very light polish later . . .

 

Acrylic crystals in watches are stressed when they are fitted to the case. The material,is flexible enough to withstand installation. Over time, it is not uncommon for these crystals to develop cracks such as yours did, as the acrylic hardens.

 

Sometimes called crazing.

Interestingly enough I've seen it more often in Omega crystals than generic ones. Perhaps down to their specific formula for crystals.

 

Y'ever smack your watch into a door knob or handle? I have!

Sucks not having depth perception....

 

This crazing happens over time, and isn’t the result of damage from an impact.

I’ve seen it on all shapes of crystals from all sorts of brands.

It’s just the nature of the material and the way it’s fitted.

Cheers, Al

 

I still break 'em sometimes! Last one was an original glass crystal on a 1917 Omega "trench". Replaced it was plastic this time.

 

Crazing looks different than a break from impact...this is impact damage:



This is crazing:



And the OP's is as well. I've even seen this on modern Panerai's that use acrylic crystals...so how fast it happens depends on how the watch is used (how much sun exposure, temperature changes, etc.).

Cheers, Al

 

Any chemist will tell you that ALL plastics become less pliable, more brittle and degrade over time. Sun exposure hastens the process.

 

Would you mind sharing the reference number of that Seamaster? I quite like it.

 

Case number is 168.022

 

Here is another example of acrylic crazing, it happens. Thankfully due to help from a couple of top notch members this is about to be remedied: