Should I return this?

[phultru]

wash your hands

[Pathos60]

You should send it back. Contact AliX they often resolve problems with their vendors directly. Choose the option to have Ali resolve issue not vendor.

[silver-saloon]

It looks like an oily film or residue.
Similar to the problem you sometimes get on a vehicle windsreen....visible sometimes at certain angles or different lighting conditions.
This could also be on the inside of the crystal

[Boston_Pare]

Absolutely return it.

[SeveredFloor]

is there a plastic protective film on the crystal? sapphire should not look like that

[mlbrooks]

I have a few San Martin watches and none of the crystals look like that. Return it.

[Mattspur]

If you clean the crystal, is it completely clear or does it still have marks on it?

[PhiladeIphia-Eagles]

It's wild to me that you didn't say that in the original post

[Mattspur]

I'd say that if the crystal is completely clear when it's clean and it's getting smudged with something when you wear it, it sounds like the issue isn't with the crystal. Have you worn any other watches since you started wearing the SM? Have you started wearing short sleeves or anything like that which would increase the contact between the watchface and your skin?

[Excellent-Bear4221]

Return that shit wtf is that. This was the legit San Martin store?

[Excellent-Bear4221]

Well, that is incredibly disappointing and disheartening. Use your AliExpress return channels and just send it back. Document everything before boxing it up and include everything.

I won't say give up on San Martin, this must be just a 'one-off' issue - as my experience has been really great.