Can someone help me identify the discolouration shown here. I first thought it was rust, but on seeing it with a loupe I am not so sure. It doesn't look like any rust I have ever seen. There is no flaking or crumbling going on just a smooth brownish discolouring.

 

My bet is debris

A good cleaning in the supersonic cleaner, with the crystal removed, should do the trick

 

Possibly. It's very smooth though, doesn't look as if it would shake off.

 

Run it by @Mad Dog , he might know something

 

It is dirty underneath your bezel. Between the bezel and the crystal. Had it also on a previous speedy..

 

Looks like dirt around the rim of the crystal. It shows up apparently because the black crystal tension ring is missing on your watch.

 

I ended up swapping the crystal and tension ring on mine. Here are a couple pics of before and after.

 

Was the crystal replaced?Any before pictures?

 

Even if the crystal wasn't changed, it should still have been taken off for cleaning.

 

No crystal not replaced. I'll contact the watchmaker and find out what is up. Weekend here so no go. I think I left instructions to only overhaul the piece and no polish! After I bought it it went straight to the watchmaker who serviced it and kept it safe until I got back into the country and had it sent to me. So I haven't actually had it in my hands before this week. I would have thought sticking in a tension ring would have been a given. Are they perhaps difficult to source?