Just finished clearing the whole map (Except for a few gray stones), and the brick in the top left corner. Due to mistakes at the very start, three gems were up against the wall in an uncombinable orientation, so I pushed all the rest of my gems to the same wall. Really fun game, whish the wall was only 4 thick though, then I could have gotten out and found a second ending :(
Not that close I'd say. I've managed to get to here (also grey rock is more appetite efficient as it takes only 640 appetite per white gem as compared to 900 from a metal)
There was 1 gem from eating all bring and grass, and two more from spending the appetite. To merge two greens we therefore need one more blue gem, and that is a lot; it just appears to look much less due to all of these compressions