Hello firefighter254 !!

A coin very nice ... You are a great hunter of relics. Never mind that the cleaner coin ,the patina of return in 20 years (or you can make an artificial patina) , I only a silver coin each month and always the destruction at the time of cleaning ...... in my country only silver coins in the hands of pirates or under the Ocean.
Home-made oxigenization:
You should not be a chemist to do that. You should come into your bathroom and find a liquid for the lime and rusting removal.
The cleaners, containing ant acid or alkali, are not suitable. Take a cleaner with hydrochloric or phosphoric acid and put gloves on your hands. The home acid cleaners are viscous, dense. They will give you dark black oxide or so called rainbow patina on a silver coin.
What kind of patina you will obtain is not possible to guess due to the great difference in the coin alloy components and because any coin has a microparticles of other metals on the coin surface, which give indeed a multicolor instead pure silver patina (it’s black).
Non-oxigen patinization:
Many people know that good black patina can be created by using photographic neutral fixative (sodium sulphite), which acts in this case in the same way as in photographic process. It contacts with insufficiently oxidized molecules of silver and forms a sustainable compound of the black color. It’s sustainable in chemical sense, not in physical one. A sulphite patina can be erased with tissue or washed out with soap. Many couterfeited coins, which we can find at Internet, contained a bit of silver, cast of aluminum or zinc, can be oxigenated at home in order to make us happy bidders.
There is only one thing that has no solution .....
Greetings!