@Archer closes this possibility rather handily in the other thread:

 

These are mostly unanswerable questions on a forum, and you would have to get the "why" answered by Omega, so good luck with that.

Anyway, let me provide some data on the crystals...first this all the data I have on the Plexi crystal:

REF: 063PW5139

063 DIAMETER D1: 34.11 MM

063 HEIGHT TOTAL H1: 5.31 MM

063 PROFILE: CONCAVE

063 TYPE: ETANCHE

DIAM OF THE GLASS SEATING D2: 34.00 MM

000 MATERIAL: GLASS PLEXI BLACK RING

000 MATERIAL TYPE: Hésalite


This is the "old" Speedmaster with the Sapphire crystal, so the 31130423001006 Speedmaster:

REF: 062SL5005

062 DIAMETER EXTERIOR D1: 34.20 MM

062 HEIGHT TOTAL H1: 4.65 MM

062 INSIDE RADIUS R2: 143.20 MM

062 OUTSIDE RADIUS R1: 145.00 MM

062 PROFILE: CONCAVE

062 THICKNESS TO CENTER L4: 1.80 MM

062 THICKNESS TO FLANGE L3: 1.85 MM

000 MATERIAL: SAPPHIRE


This is the crystal for the "new: 321:

REF: 062SNZ013040

062 DIAMETER EXTERIOR D1: 34.20 MM

062 HEIGHT TOTAL H1: 4.65 MM

062 INSIDE RADIUS R2: 143.20 MM

062 OUTSIDE RADIUS R1: 145.00 MM

062 PROFILE: CONCAVE

062 THICKNESS TO CENTER L4: 1.80 MM

062 THICKNESS TO FLANGE L3: 1.85 MM

000 MATERIAL: SAPPHIRE

And finally the crystal for the new 3861 sapphire Speedmatser:

REF: 062SNZ013177

062 DIAMETER EXTERIOR D1: 34.20 MM

062 HEIGHT TOTAL H1: 4.65 MM

062 INSIDE RADIUS R2: 143.30 MM

062 OUTSIDE RADIUS R1: 145.00 MM

062 PROFILE: CONCAVE

062 THICKNESS TO CENTER L4: 1.70 MM

000 MATERIAL: SAPPHIRE


So all these are quite similar, with the exception of the plexi, but on that one no dimensions of the inner and outer radius are given unfortunately. All of these are "domed" so are concave as Omega's description indicates, and for the sapphire variants the differences are quite small.

Regarding the potential drawbacks in "strength" that you asked about, the only thing that indicates anything in the regard is the water resistance, and all of these are listed at 5 bar.

Cheers, Al

 

I’ve now read the other thread provided by @STANDY, and have a few thoughts as are relevant to this thread.

And viewing this thread as different from the prior thread in that (1) we now have the “domed” sapphire of the cal.321 to compare to either the 60th Ann. domed crystals and the ‘regular’ speedy sapphires, and (2) the prior post was a pre-cal.3861 musing on what it’s sapphire might be like, which now may be given a post-mortem.

But first, having learned from the prior thread’s discussion, a terminology correction per @Archer’s directions there:

From a general watchmaking perspective, the regular speedy’s sapphire is also “domed,” insofar as the crystal has any concave feature whatsoever (as compared to a “top hat” type sapphire, completely flat).

From there, though, I add that Omega’s marketing materials have a slightly different approach to terminology in that the basic marketing/product materials appear to describe the regular speedy sapphires simply as “sapphire”, while the marketing product materials describe the 60th Ann. and cal.361 crystals as “domed sapphire.”

Accordingly, the notion of “domed” used in watchmaking is to that extent different from Omega’s marking terminology regarding “domed.”

That terminology quirk laid out (especially in order to not irk the watchmakers amongst us - and I’m all for precision in terms): I’ll here use the terms “regular sapphire” and “domed” as implicated by Omega’s marketing speak.

Turning to the substance of the other thread, the most compelling (only?) functional trade off of domed vs regular sapphire was suggested to be that domed sapphire necessarily results in optical refracting and distortion that are unpalatable. On this view, Omega could make more domed sapphire to address the milky ring, but in doing so would introduce other issues (that perhaps Omega finds more repugnant than the milky ring):

Only now in retrospect with the cal.321 domed sapphire in hand can we say that this reflection/distortion concern appears to have either been incorrect or overcome by the cal.321’s sapphire design.

But it raises a new and interesting (is anyone even reading anymore?) question about the “dome” of the 60th Ann. vs the cal.321. In a subsequent post I’ll include pictures of this comparison, but my armchair take is that: (A) the cal.321 is somewhat less “domed” than the 60th Ann., but (B) the cal.321 manages to have less milky ring, less refraction, and less distortion than the 60th Ann. sapphires.

If so, then it is possible that in the cal.321 Omega managed to find a solution in simultaneously using less dome, but achieving a reduction in all of milk/reflection/refraction.

If nothing else, with the cal.321 in hand, the prior thread’s suspicion that a domed sapphire would require undesirable reflection/refraction seems to have been an obstacle overcome.

Ans, now with cal.3861 in the wild, the prior thread’s aspiration that Omega address the milky ring in the the model’s sapphire appears to have gone unfulfilled - based only on pictures/videos seem to date, and the fact that the cal.3861 has not been offered with the “domed” sapphire similar to the cal.321.

So, for those on the prior thread hoping Omega would address the dome/milk sapphire issue in the new model, the post-mortem appears more discouraging than they could have anticipated: not only did Omega not address this in the new cal.3861, but Omega did not address it even though the cal.321 proves they had the option to do so.

What’s still not settled, though:

(1) were there material functional costs other than milk/reflect/distort that caused Omega to not use the domed crystal in the cal.3861? (If good reasons, the .3861 hopefuls may be glad to hear the benefits, while the cal.321 hopefuls may be interested to know the costs)

(2) to the extent the cal.321 dome sapphire in fact bears the 60th Ann. in terms of milk/reflect/distort, is that improvement the result solely of the cal.321 sapphire design, or instead involve other design differences (eg the polished rehaut on the 60th Ann).

(3) given how maligned the milky ring is, and given how the cal.321 was marketed toward a type of “I want it modern but with all the charms of vintage” buyer, why hasn’t Omega remotely marketed the angle of “hear us out: yes our cal.321 has used sapphire unlike the original Ed White, but we have created a domed sapphire that appears remarkably close to hesalite”. One strange answer would be Omega didn’t notice (very un-Omega like). Another equally strange answer is that it’s an Easter-egg feature Omega is playing cool (also very un-Omega like).

Personally, and this is obviously pure conjecture, the pessimist in me finds it most likely (absent better suggestions) that either (1) there’s a trade off in the cal.321 dome benefits they don’t want to tell cal.321 owners, or (2) there’s a trade off in the cal.3861 sapphire the don’t want to tell the cal.3861 owners.

But the optimist might say that Omega intends the cal.321 sapphire benefits to delineate the lines, while not rubbing in the faces of cal.3861 owners?

 

Posts passed in the night; thanks, Al

No doubt the minutia may have no answers at all, or even if they did be only in the minds of people I don’t know.

But we’re that the qualification of utility in this forum, we’d be left with posts only about MSRP prices, dogs, knifes, guns, politics, and made-up satirical Omega adds that turn on puns about muff-diving. Of these sorts of things, holidays with the family gave me my fill (other than the latter satirical add, but maybe only because my family doesn’t include any 13 year old boys who still haven’t performed the deed themselves).

 

Not just that, but the “old” sapphire and the cal.321 appear identical on all these specific metrics.

That said, the measured height can be identical while the slope to height different. This indeed seems the case to the naked eye: the old sapphire appears to rise quickly at the margins leaving little rise from margins to center; the cal.321 appears to rise less at the margins, and so reach the ultimate identical height more gradually.

But I suppose it’s obvious on reflection that knowing only the diameter, height, and radius of a 3D object only tells you so much about its contours.

 

Well, what Omega uses in marketing materials is different than what they use in technical communications. If you note above the first crystal they call is "hesalite" in one section, but also call it "plexi" in another. The "Delrin" brake that people go on about is described thusly in the technical documentation:

72208601726V2 | PLASTIC BLOCKING LEVER

In the technical documentation, all of these are "concave" according to Omega. It's not about "irking" anyone, but about a common language where we all know what each other is referring to.

Just to be clear, the 60th Speedmaster is not sapphire, but plexi. For the SM300, the crystal dimensions are as follows:

REF : 062SNZ006634
002 WATER-RESISTANCE : 30 bar
062 DIAMETER EXTERIOR D1 : 29.50 MM
062 HEIGHT TOTAL H1 : 4.45 MM
062 INSIDE RADIUS R2 : 48.30 MM
062 OUTSIDE RADIUS R1 : 50.55 MM
062 PROFILE : SPHERICAL
062 THICKNESS TO CENTER L4 : 2.25 MM
062 THICKNESS TO FLANGE L3 : 2.41 MM
000 MATERIAL : SAPPHIRE

So here the profile is called "spherical" rather than "concave"...

For the sake of completeness...this is the Railmaster Trilogy:

REF : 062SNZ006109
002 WATER-RESISTANCE : 6 bar
062 DIAMETER EXTERIOR D1 : 33.10 MM
062 HEIGHT TOTAL H1 : 4.55 MM
062 INSIDE RADIUS R2 : 250.00 MM
062 OUTSIDE RADIUS R1 : 251.50 MM
062 PROFILE : SPECIAL
000 MATERIAL : SAPPHIRE

This one is "special"...

I can answer these questions, but it seems you are reading a lot into this...

Cheers, Al

 

Sure this has bothered me too, so I have read everything related here too. Since I am the newbie I didn't want to jump in
I just have a modern hesalite Moonwatch and was thinking to get the new with the sapphire if it has no milky ring, since the new Ed White shows it is possible.
Now I don't care anymore about the new Speedmaster and definitely hope one day also to get the new Ed White

But what I wanted to say: I think Omega just wants to keep the milky ring for the "standard" sapphire Moonwatch since there it always had that milky ring and it distinguishes additional from the hesalite version. Not overthinking it.
And for very special watches like the new Ed White caliber 321 they go that extra mile do give us something special (robust sapphire without a heavy milky ring that would feel like ruining this special watch).

 

Very interesting topic! Thanks for pursuing this analysis, & kudos to Archer for the technical data points.

Scrolling through old photos on my phone, I definitely see the milky ring now on the 60th SM. Especially in close-ups from angles like this:



It didn't jump out at me during daily wear, when worn on the wrist. Or when laid side-by-side with a Hesalite Pro.





Especially in comparison to this:



I'm definitely one of those in the camp of: "I'd be much more willing purchase a Sapphire Sandwich if its crystal was curved like the 321 Ed White's crystal, and had less of a milky ring".

 

Be honest cv, what you are really saying is that you would have preferred your Ed White with plexi :

 

The “irking” was total gest, and solidarity -
as I’d hoped my follow on would have made left no chance of miss communicating:

Yes, good clarification: in my original post I’d singled out the non-speedy 60ths as being the sapphire, but from there used just 60th short-hand and the nuance could be lost - indeed, I had missed that your original dimensions quote was for the 60th speedy, not the other two!

Bracketed inserts mine, above: this is great info regarding Omega denoting a difference between all three of the sapphire tributes with shapes colloquially called domed by many.

Your, and my, thrill at precision in terms grows.

But at the same time, some things are made less clear. Now it appears that somewhere in Omega’s marketing materials they called the new cal.321 “domed” (as evidenced by several third party ‘reviewers’ recounting such description when rattling off the obvious promo content), but the technical materials make no distinction among “concave” amongst the cal.321, old sapphire speedy, and new sapphire speedy ... while at the same time giving each of the sapphire 60ths two different descriptions.

I almost dig into the measurement differences between the three 60th and cal.321 crystals, but remembered that really the few dimensions given don’t tell much about the contours.

Well, these confusions are moderately frustrating to the 3 people reading this thread (not counting @Archer, who is basically here working charity) - which group of 3 appears to not motivate Omega to lengthy explanation

 

I’ve never intended to hide my very strong desire for Omega to have (1) given me a plexi option, (2) given it to me - but only me - for free, and (3) have raised the MSRP 3x

 

Dont worry, i am sure there are more people reading; at least i am reading with great interest! thank you for your effort guys!

 

Wow I knew this was an over analytical group but this topic takes the OCD to a whole new level.

Since I own a variety of speedmasters including a 321 I’ll add some photos here that might help.

321 v 1861 hesalite






321 vs Apollo 11 50th sapphire




321 vs CK2998 pulsometer sapphire





I’d have taken nicer photos with a nicer camera but I’m lazy and this is what I have time for. Hope this helps.

edit:
this NTTD also has omegas domed sapphire:

 

@Archer, for the sake of completeness, could you please look up the dimensions of the Speedmaster FOIS - "First Omega in Space".
Thank you!

 

Same as the old Speedmaster...

 

Nice, maybe during service one can ask them to put the 321 crystal as they share the same dimensions.

 

For good measure here is a better photo of 321

 

Wow nice collection

 

Thanks!

Doubtful. Omega service, if anything like Rolex won’t install parts that aren’t original equipment to the watch. You could probably ask an independent watch maker to do it.

 

And when you do, please report back, as I suspect the every would uncover whether, if at all, anything about the cal.321s rehaut, ceramic bezel, etc., explains the lack of expected sapphire qualities.

Speaking of the cal.321s lack of expected sapphire qualities:

When I scroll through these comparison pics, it seems pretty obvious - to my eye - just how much the cal.321 lacks those qualities compared to other sapphire speedmaster offerings, and how much more similar the cal.321 sapphire appears to the plexi speedy offerings. Not complete in either direction, but worth remark.

Having spent a lot of time attempting to understand Omega’s 1970’s sports watch offerings, the current conversation is a lackadaisical stroll through a mere 15-20 variants and complete lack of at least contemporary information.

I admit to feeling increasingly self-conscious about this level of scrutiny on such an arguably inane nuance. But then I glance towards the threads on, e.g., end link modifications and script curvatures in the letter “e”, and realize the line is long to the nut house.