The sapphire bezel insert on the O7 is made the same way all sapphire inserts are made: recesses are filled with lume from the back and then the whole thing is sealed before installation in the bezel. The air bubble probably lies between the sapphire and the black paint/sealant. Like I said, it's not a big deal to me and the bottom line is that IME a sapphire insert seems more durable than an acrylic or mineral (rare, but a company or two tried them) glass insert. I am almost always taking photos when diving and so my watches tend to take a beating.
My issue with the SMP1200 hand is that it is anodised orange. In low light conditions and because it's behind a thick sapphire crystal and buried in the deep face of the 1200, it tends to look brown or black instead of orange - unlike the fluorescent orange of the more recent SMP600 hands or a few other modern watches using plongeur hands. The SMP1200 minute hand only looks orange when it catches the light just right.

Dive was off of Rottnest Island. It was an OK dive, but nothing spectacular. Pretty good surge that day and vis was just OK. I'm sure there are better spots, but I was limited on time. The crew (Perth Diving Academy) were super and made the best of average conditions: