If you were to lightly pollish the whole cymbal, those "dots" would be all over the entire thing !!

It looks like someone hit that with a wheel !!

Ummm. Tricky. I've experimented with a number of patina formulas, but one of the first things I discovered is that patina formulas tend to remove the existing patina. That is scary. It means you have to be willing to lose all the existing patina (or have it all go spotty) on the way to getting an even patina back again. If you are brave:

Cut a lemon in half and sprinkle some salt on each half. Take each lemon half and rub it all over the cymbal with the cymbal horizontal on some protective surface like newspaper. Don't make the juice so thick you get drips. Wait for it to dry. This may take hours or overnight. That's fine. It is the drying time which promotes oxidation. Repeat this cycle of lemon and salt and letting it dry a number of times.

You will find that you get green forming not the nice brown you want. Do not be afraid. The green can be rinsed off at the end, leaving the nice brown behind.

An alternative to the lemon method is vinegar and salt, and application with some sort of brush. Another alternative source of patina solution is pickle juice.

There are lots of more complex chemical formulae available on request.

I just remembered that I've got a cymbal to do this with. Similar issue: a few partly cleaned patches compared to the rest. If you want to wait for a week, I'll probably have tried mine and I can document it with before and after photos.

The only other thing is that the reaction of the metal depends on what sort of alloy it is. I'll be working on B20. I'm not sure what that Stambul will be. The Paiste-only Wiki says B8, but the stamps aren't like yours. And RaBe's cymbal page says Stambul is NS12 but the Stambul 65 is B8.

I know from reputation that B8 responds much more quickly than B20 to patina formula. I have no experience with NS12 at all. It could be a whole different thing.

You might get more info from the people at Paiste-Only. There is a thread with stambul stamps and those guys know much more about these than I do.

they sell kits for oxidation of certain metal, copper as in new gutters or exterior treatments and it ages them 100 years its a matter of the right chemicals and u can too, age your stuff some paint stores sell the kits