Breitling Navimeter World Automatic Chronograph Men's Watch A2432212/B726

Where can I find info about the evolution of crystals?
On modern watches I take the type of crystal to be one indicator of quality. When looking at vintage watches, however, I don't have any idea what is considered a good quality crystal. I wouldn't consider buying a modern watch for more than a minimal price if it had a glass, plastic, acrylic, etc. crystal. However, I have no idea when mineral and sapphire crystals started being used. For that matter, I'm not really sure what a sapphire crystal is, other than that it's more difficult to scratch.

Old Accutron (tuning fork) repair
I have an old Accutron watch (tuning fork) that now longer runs. It hasn't run in years. It dates to the late 1960's...a high school graduation gift. (Man, I'm getting old!) Does anyone have any experience in having these watches repaired? I've tried locally without much luck. Most folks I've talked to say, "It probably needs parts, and I have no parts."I notice lots of folks on the web offering Accutron repair services. However, without a recommendation, I'm hesitant to send my watch off to an unknown party. If you've had an Accutron tuning fork repaired, perhaps you'd be willing to share your experience and a name with me?Thanks for any help.Van

Just got my Breitling Navi TT back from Breitling USA
I sent my breitling out be serviced. I am glad to be reunited. Sent from my PC36100 using Tapatalk 2

How long is too long?
One of our Omega Seamasters stopped running and I posted in that regard several weeks ago. It was under warranty and has been sent to a service center. How long it too long to wait to get it back?

Help finding a new SubC -116610LN
Here is a little bit of the story. So I own a Y serial purchased new in 2003 in my collection. It has a little family history behind it through the years. I wear it quite a bit in the rotation. I always said that when my boys graduate from college they would get a watch handed down. Well my first boy is going to graduate next year with his engineering degree from SDSU. I will be giving him my Sub. I would like to replace that sub with another in the most current version.Fast forward to the last few weeks and I am surprised to see the lack of availability on the standard sub. I get and follow all the fuss with hulk (own one), BLNR, Daytona etc etc. I called up my AD that I use and no luck. She does not have one. Then I started looking at lightly used or second hand BNIB and see the grays are almost at new retails. For that price difference I would go AD all the way.So is a SubC really that hard to find? or is my AD just not a high enough volume dealer to have one?Lastly, if an