Plexi Crystal Top Glass on Oris Big Crown

[john007]

I am in the process of purchasing my first Swiss made watch and was considering the Oris Big Crown with pointer date. I was somewhat dismayed when I discovered that the top glass is called "Plexi Crystal". Is this really plexiglass? How well does it hold up and can it be replaced with a saphire crystal. I was a little surprised to find this on a watch that otherwise appears to be of high quality. Thanks for your input.

:thanks

[Chris Hohne]

I don't think you can replace with a sapphire crystal - the plexi is domed. I kind of like my BC with the plexi - it has a "warmth" the sapphire does not. It also gives it a vintage feel. Don't worry about the plexi - it is more resistant to shattering than sapphire, and can easily be polished out if you get any scratches. There is a product, I believe it is called Polywatch, that is supposed to work great.

Chris

[Fitzer]

My Big Crown Commander is now about 10 years old and hasn't picked up any scratches yet. The plexi is in keeping with original pilot's watches which had plexi crystals. I can also attest to the fact that Polywatch works extremely well, I have used it to polish out scratches on cell phone screens amongst other uses.

[kontai69]

I was somewhat dismayed when I discovered that the top glass is called "Plexi Crystal"...I was a little surprised to find this on a watch that otherwise appears to be of high quality.

I too use to think that plastic crystals = cheap. I then learned that several new expensive watches (eg Omega Speedmaster Moon, Sinn 356) come with domed acrylic plastic crystals, most likely for historical/traditional reasons. Also, domed sapphire crystals are extremely expensive.

But like others have said, Polywatch will perfectly remove minor scuffs on the plastic.

[john007]

Thanks for the great input here. I am new to this "hobby" so I appreciate your sage advice and guidance! I really like this particular watch and am glad to hear that the plexi crystal isn't a quality issue.

[relo ni leroy]

From what i've learned here(wus), authentic pilot's watches don't use sapphire crystals because they shatter more easily compared to the plexis. Correct me if i'm wrong guys.

[Maple]

Yes, that's my general understanding.

Choose Saphire Crystal if scratch resistance is your main concern.

Choose accrylic if impact resistance is your main concern.

[flame2000]

I was hoping Oris would replace the domed plexi crystal with sapphire crystal since Sinn had equipped their 356 Flieger with the domed sapphire crystal. My last big crown picked up an awful lot of scratches on the plexi glass after 6 years of use. Some were pretty deep scratches.

[sto1967]

My Big Crown Commander is now about 10 years old and hasn't picked up any scratches yet. The plexi is in keeping with original pilot's watches which had plexi crystals. I can also attest to the fact that Polywatch works extremely well, I have used it to polish out scratches on cell phone screens amongst other uses.

Where can you get this polywatch? At a watch store? Can you use toothpaste as well?

[Zavato]

I was hoping Oris would replace the domed plexi crystal with sapphire crystal since Sinn had equipped their 356 Flieger with the domed sapphire crystal. My last big crown picked up an awful lot of scratches on the plexi glass after 6 years of use. Some were pretty deep scratches.

Certainly sapphire is far more scratch resistant, must what acrylic has going for it is that 1- the crystals tend to be inexpensive, and thus are reasonable to replace, and 2- polywatch does work reasonably well on minor scratches (readily available on eBay).

Some manufacturers that use sapphire crystals use ant-reflective coating on both sides of the crystal, and the AR coating is far softer that the spphire, so even if you have a sapphire crystal, you still could wind up with a marred crystal.

It was mentioned Omega uses an acrylic crystal. They do on the Speedmaster "Moonwatch". The current version of the watch is flight certified by NASA. Acrylic, because it is softer, isn't prone to shatter, and I guess inside a spacecraft, you really don't want little bits of crystal floating around getting into who knows what.

Currently, astronauts are permitted, though to bring personal watches on board the shuttle, but for any EVA, it's the Omega they wear.

So, acrylic definitely has 'history' and it has some practical reasons for its continued use.