1988 Silver Eagle

With these, if you haven't touched it, dropped it or hit it with something, they will almost always grade MS69 or 70. Most are probably 69 with a fair amount of 70s. I've seen a few MS68s, but they are few and far between. Yours looks to have some toning on it that isn't too attractive, but that doesn't mean it will necessarily lower the actual grade. I can't really grade it from the pics provided as it is most likely a high MS coin. However, I would say that a grade for this coin doesn't really matter much as it is just bullion and it's value is inherently tied to the price of silver.

Just to note. A 70 is supposedly a perfect coin.
A tiny ding somewhere on the rim drops that down
at least one grade. I have never seen an ASE from the mint
that was a 69 or 70. Not that there have not been some found. But 67 through 70's are pretty scarce from a roll. No idea on this particular coin as it would have to be graded in hand
unless an obvious defect is seen in a photo or scan. But from what I can see on this coin it is not a 70,69 or 68.
Just my opinion anyway. Still is a very nice coin though.