I just went through your steps, and the first few gems it wasn't working but after like the 4th gem the next 3 gems did make new IDs. That is a scary thought. There has to be a limit somewhere, 8 digits with 16 possible values has a limit somewhere. I don't understand how to do permutations with hex values so I'm not even going to attempt it, but lets just hope that the well dries up.
Edit: But it makes me wonder... maybe the possible IDs it gives you are static. Meaning that you enter Makna Forest for example, dump some IDS, run down the path, slay a few monsters, check again you have new IDs now. Maybe the method you found gives you all the possible IDs for the area before going through all that crap, and maybe they are reused again (like IDs you dumped through gem crafting may end up being the same in like Sword Valley or something). Hard to say since at any point you can't actually check which textures are being loaded by Dolphin.
Edit: But it makes me wonder... maybe the possible IDs it gives you are static. Meaning that you enter Makna Forest for example, dump some IDS, run down the path, slay a few monsters, check again you have new IDs now. Maybe the method you found gives you all the possible IDs for the area before going through all that crap, and maybe they are reused again (like IDs you dumped through gem crafting may end up being the same in like Sword Valley or something). Hard to say since at any point you can't actually check which textures are being loaded by Dolphin.