295C Crystal Question

[hologramet]

So let's do a little necro-bump.

>> I'm looking at double-domed sapphires for a 116110 Noob-project.

The only candidates seem to be:

Candidate 1: 

Type : Double-Domed 
Diameter (Size): 30mm
Thickness : 1.8mm
Height: 2.6mm
Material : Sapphire Crystal

http://www.ebay.com/itm/301642988489?_trksid=p2060353.m1438.l2649&var=600504451449&ssPageName=STRK%3AMEBIDX%3AIT

Candidate 2:

Type : Double-Domed 
Diameter (Size): 29.5mm
Thickness : 1.8mm
Height: 2.8mm
Material : Sapphire Crystal

http://www.ebay.com/itm/301719925440?_trksid=p2060353.m1438.l2649&var=600553582169&ssPageName=STRK%3AMEBIDX%3AIT

Candidate 3:

Type : Double-Domed 
Diameter (Size):29.5mm
Thickness : 1.4mm
Height: 2.5mm
Material : Sapphire Crystal

http://www.ebay.com/itm/29-5mm-Sapphire-Crystal-Watch-Crystals-Double-Domed-Height-2-5mm-x-Thick1-4mm-/291476051243

Candidate 4++

30mm thick: 1,5 // 30,5mm thick 1,2 // 30,5 thick 1,0 // 30,5 thick 1,3

 

>> Which is the most suiting one? Which gasket should I use? Any Clarks or similar gasket would help. 

[hologramet]

Anyone?

So a "regular" crystal is 29.5 mm in the "mounting" part C. And 30.4 mm in the visible part A. I'm guessing the width of a gasket is about 0.45mm. Then we have the height E...

Since the double-domed sapphires aren't available with a lip, I guess the only option is getting one that is 29.5 (C) with a thickness (D) of 1 to 2 mm. 

Should I use an I-formed nylon gasket or an L-formed? L-formed right? Then I can do:

How high is b? Because I don't want the sapphire to be "too" recessed, neither do I want it too high?

---

Please any tips?