New crystal for my Longines Ultra-Chron Ref. 8455

As part of a time-honored tradition in being the new guy on a message board, I would of course like to ask a question ;-)

My watchmaker is currently working on one of my recent catches, a Longines Ultra-Chron Ref. 8455. He already did the service on the movement, and it's running great (at something like +1 to +4 secs/day, will see more once I pick it up). The nice people at Longines have already sent me an Extract from the Archives, so I know the watch was originally sold in Hong Kong in 1973, and has the 6651 movement with 25 jewels beating at 28.800 bph.

So everything's great, right? Sadly, there's one little thing that's not the way I want it to be, so I'll show a picture of a watch before the actual service (which I don't usually do - I prefer showing things when they are bright and shiny). Problem is, the acrylic crystal has a small crack in the glass - see below:



Now, the watch isn't in perfect condition anyways, so I may be able to live with it ... but if possible, I would like to have the crystal replaced. My watchmaker hasn't been able to find the correct crystal, though, which has me a bit baffled - I didn't know the crystals were that special.

I tried to contact Longines, and they sent me a nice reply, but basically they said that they would be happy to solve the issue after I send the watch to them, and they wouldn't sell the crystal to me directly. Hrmm. I also tried looking in the databases of Jules Borel, Boley and several other places that I usually pull parts numbers from, but no dice.

Does anyone of you have an idea where I could source the crystal from? Or a parts number (maybe from the Sternkreuz glasses, or anything else) that my watchmaker could use to order one?

Your help is much appreciated!

I wanted to post a quick follow-up about the crystal, because I got another mail from Longines.

So, I don't have a parts number or an idea about the correct replacement crystal, but what wasn't originally clear to me is that Longines has the correct part in their workshop. They are just not selling it to the public or independent watchmakers, which I can understand - that way, they keep the parts so that they are able to do the service themselves. If I absolutely have to have the crystal replaced, I can send the watch in and they will replace it for me - good to know that the option exists.

In the meantime, maybe my watchmaker has an idea. If not, I'll go with the old crystal for now, and maybe replace it at some later date. I'll update the post later, when the watch is back from service, so that we have a "before-and-after-shot" in this thread.

You were kind enough to give my Longines Admiral a ‘like’ earlier but that has a generic crystal …. if this helps?

Your Admiral is really nice to look at - I'd give it five stars if it didn't already have them ;-)

From what my watchmaker told me, the Ultra-Chron in question needs a crystal that he didn't find a generic replacement for (so far). Maybe that has changed... I would certainly hope so. In that case, I definitely wouldn't mind a generic replacement.

As far as I'm aware, Longines crystals aren't signed the way Omega (acrylic) crystals are, or are they?

TBH, I’ve no real idea about whether or not Longines crystals are signed but @LesXL or @seekingseaquest have quite a few and it may be worth contacting them. Where are you located?

I'm located in Germany.

Thanks for the tip! I'm still holding out hope my watchmaker has found a solution, I'll know more when I see him next (which will be in two or three weeks, I think).