The White Smoke Monster
When Locke says something along the lines of “I’ve looked into the face of this island… and what I saw was beautiful,” it is reference to a scene where Locke saw the “monster,” but the audience never sees what John is looking at. He could have actually seen a white smoke monster – the manifestation of Jacob (assuming that his Nemesis is the black smoke monster)

for me, i don’t see why Locke saying that what he saw was beautiful would make people assume it was white…to me that just imply’s that he looked into the usual black smoke monster and what he saw was beautiful. I think thats a big assumption you’ve just made.
what she said.
I think he was scanned and bc he was good the smoke most has always been choosing Locke for the whole loophole thing
The smoke monster looked upon the rest of the Losties with disdain and the hate he has for mankind. He showed them things that would get them to feel guilty so he could manipulate them when he wanted. When he presented himself to Locke though, he (smokey) was looking at the tool of his master plan. The creature that was going to bring him his loophole and the end to this game, and his nemesis Jacob. That’s why it appeared different to Locke; 1) Because may have had some sick affection for Locke, and 2) he didn’t want Locke to have any negative associations with the island. He wanted him to think it was all great and not think that there was possibly an evil entity that meant people harm.
Locke used the word “white light” when making that description.
and we now know who the smoke monster is…
I only consider this a possibility because we (the audience) never saw what Locke saw, and that might be intentional. Also, Jacob and Mysterio seem to be opposing forces that are nonetheless equal beings. If Mysterio can turn into a smoke monster, why cant Jacob?
True it does seem strange that Jacob and MIB would have different powers but then maybe they are not the same creature for the fact that Jacob can be killed by such a weapon like a knife and MIB/Smokey can take bullets and not die.