horrid seams, thickness isn't consistent across the o ring itself nor among the o rings, etc.
This would indicate you received rings made in china. Request the compound polymer and cure date this request normally avoids suppliers selling you out of date Chinese made junk.
This was done to not spend a fortune on getting official shearwater o rings, foolish be me, would have been cheaper now... 12.37x2.62, that should be correct?
The dimensions you quote would indicate a BS 112 size
Am I just being picky? Or do others think the quality on the images also leaves something to be desired? (Blue is shearwater)
In a world of junk buying 0 rings as a retail customer on the internet in small quantities for precision applications is a very difficult position to be in even from scuba sports suppliers.
But that's not your only problem. Shearwater and that colour blue.
In engineering blue rings used in the past to indicate a Fluorosilicone compound material rather than the common black nitrile rubber buna N or Viton materials and compounds but not anymore. Clowns in the industry have started adopting cheaper coloured rings of various materials and that shade of blue in your photo is a little too blue to say it's a Fluorosilicone from my experience.
Now not knowing exactly what Shearwater use but with your suggestion of silicone grease being used as the lubricant this would suggest that Flurosilicone was used in the original and as it doesn't swell up and deform with silicone grease as say a nitrile material then your original blue ring from Shearwater may indicate that FS was used.
In addition please note that the plug in your photo is plastic (not metal) and as this may also be sealing into a plastic housing therefore again Fluorosilicone would be a good choice due to pliability deformation softness with an ability to seal without deforming the plastic plug to housing material and also with the added property to be inert to silicone grease.
However I'm still just not sure on that shade of dark blue colour my spider sense is tingling Knowing Canadian electronic companies for engineering stupidity in underwater applications it may just be a vendor supplier substitution of product material to folk who don't bother to ask.
And if you have read down this far a couple of documents enclosed below may help you understand a little of the difficulty your faced with as a small quantity retail customer using the internet to purchase critical components in a world full of lies deceit obfuscation and deception from the clowns and ignorant fools that supply. Just saying.