I think "emerald" is an endearment, either due to eye color or indicating the person is precious (I lean toward the latter). I also believe this is a song about telling a love interest that he will wait for her to be able to leave a bad situation/state of mind she is in (several types come to mind). He is advising her to do what she can to cope until she is able to leave. He is giving her strength with the knowledge that he understands and will be there for her when she is ready.
I think "emerald" is an endearment, either due to eye color or indicating the person is precious (I lean toward the latter). I also believe this is a song about telling a love interest that he will wait for her to be able to leave a bad situation/state of mind she is in (several types come to mind). He is advising her to do what she can to cope until she is able to leave. He is giving her strength with the knowledge that he understands and will be there for her when she is ready.