Are you planning to sell the coin your grandma gave you? As you can see on the page you reference, this coin has sold for very high prices but those are in much better condition than yours. Your coin, while very nice, would be graded lower than those on the page. I'd say Good but take that with much skepticism as I have no experience grading such coins. Yours also has what looks like a hole for a necklace chain which will lower its value even more. If you're serious about selling it, contact an auction house. If you're not serious about selling it and plan to pass it down to your grandchildren it doesn't really matter what it's worth to others.
I'm actually interested in selling it but I have zero knowledge as to how to do that. I am aware that this is a very old coin and that it certainly has at least some value so how easy is it to contact auction houses abroad and sell it there?
If this is a real coin, then you should contact one of the auction houses as opposed to even looking at this forum or ebay! That is a rare and quite expensive coin. Selling outside of these venues will be good money lost. See cngcoins.com or heritageauctions.com for some ideas. They offer free consultation on the coin and what it might be worth and how much the consignment fees will be...