Board Thread:Spoilers!/@comment-26443838-20160811151224/@comment-24674051-20160811171837

I think in any case that the phrase is primarily intended to apply to Aladdin. But maybe it is going to be attributed to someone in the main cast as well (many of the titles tend to have multiple meanings, or are intended to identify with multiple characters). And while one of the main plotlines is saviorology, I doubt Emma is the diamond in the rough (by either of the definitions provided).

from the main cast, the characters that I would consider as diamonds in the rough are Belle, KIllian, Henry, and Zelena. and I'm going to go with Belle, and guess that she may be interacting with Jasmine in Storybrooke.

And I agree that the episode title confirms that it relates to the Aladdin Gang (and strongly intimates that we will see one or more of them in present day Storybrook).