1890-O Morgan Dollar

Looks MS to me. If those are the seller's pics, they could be doctored though.

I'll say AU-58.

From the pics,
I would think that a range of grade opinions from AU-55 to MS-64 may be posted.
There is weakness over Lib's ear that I think may be due to a light strike in that area. Same with eagle's breast feathers on the direct opposite side of the coin.

To be sure, a close examination under high magnification should be carried out, looking for undisturbed luster or wear.

My opinion for what it's worth:
MS-63.

the 90(O) was right in those years where there were strike issues at this mint which was from 86 through about 97 . typically these are seen quite soft and this one has a decent strike particularly the obv. there are a couple minor hits on the rev rim at K12-K1 not to affect anything really

some glare is obscuring luster so its difficult to tell if its broken anywhere. the coin may have had a light dip as some of the fields on both sides look a little dull. the cheek is going to make the difference on whether the coin grades MS63 or 64. reverse looks like a decent 64. all of this hinges on what the coins luster looks like in hand.

i'll be conservative and say MS63 with a shot at 64

I am at MS-63