Removing Mount

Unfortunately no matter what you do it will leave a permanent mark. You have what looks like chain wear alongside the loop and desoldering the loop will almost certainly leave some small area less tarnished than the rest of the surface.

As to how/where, any jewelry store that does repairs can probably do this, but be VERY clear you want JUST the loop desoldered with as little heat spreading onto the coin as possible and NO other cleaning or ANYTHING. Then, once you see what you have, you can evaluate if there are next steps.

You can also try to contact the certification agencies - NGC, PCGS and ANACS all have conservation departments, perhaps they can help.

I agree that the loop looks horrid, and should be removed, but mechanical means will be need to be used to avoid heat stress, if heat was used to assist.

Nevertheless there will ALWAYS be some sign left that the loop had been removed, and certainly, the coin WILL NOT gain any value.

Such coins can have the potential to be very unsatisfying to own; that has been my feelings and experience.

I bought an ancient gold Aureus of Claudius a long time ago, with a very obvious test cut. I bought the coin for about 10% (few hundred GBPounds), of the price of the equivalent undamaged coin (few thousand GBPounds) but ultimately, I just had to flip it. (IMPER.RECEPT reverse)

If you bring it to a jeweler, expect your patina to be completely lost. It'll come back white and your jeweler may want to buff it so be very specific and make sure they write down that instruction on the repair ticket. I think your best bet may be to just wear the coin on a necklace if you want it to look the same as it does now.

It's not going to look new or even aged. It'll just look retooled. The process used to remove that bail involves heat. Silver can't take a lot of heat without burning and it'll leave a nasty purple stain on the surface if you don't protect it with a certain solution. This solution comes off with acidic stuff so just know that your coin will take a "bath". There are ways around this but your jeweler must be very experienced and brave because it carries risk. Ask your jeweler about "depletion gilding" and have them explain to you what that is, as it may be your best bet to return it to a condition that makes it look alright. If they have no idea what that is run away from that jeweler.

Basically, make sure they disclose everything they're going to do with the coin. Better yet, tell them if you don't want certain things to be done with the coin, like surface changes, luster, because that solder will still be there in some form and surface treatment (filing and sanding) is needing to completely rid the area of solder. That's why the jeweler will want to buff it. So if you communicate with him/her about what you want and it's all transparent, and they're experts you should go ahead with it. That's my free advice.