The coin looks genuine, so the question becomes whether the mintmark has been added. If you are not already familiar with the diagnostics, check here: http://en.allexperts.com/q/Coin-Collecting-2297/1893s-Morgan-Dollar.htm
I am very familiar with diagnosing Morgans, as I have collected, sold, and acquired them for 40 years. This is a grading exercise, as there has been much debate about key date, and CC Morgans recently--so I tossed this out to get opinions. I know what it is.
I think it is genuine. The crossbar through the vertical of the "T" in LIBERTY is a diagnostic since there was only one die pair used to strike them.........VF20. Chris
Yes, there were only one set of dies--very limited mintages for a Morgan, and even fewer surviving. You are onto something.
This is NOT my coin, but is this one real or fake, and why do you think so? Compare it to the other one: