@wtyk, first welcome to CCF. Second, I agree with the others that this isn't a coin, but rather a round of silver. Regarding its history, while it *may* have been made in 1986, it certainly could have been made more recently. Nice pick-up from your grandfather!
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz