I'm sorry, but I cannot replicate the problem on my end. Can you please copy your "save" file inside the game's Data folder and upload it to dropbox or mega so that I can have a look at it?
Hello, your current play is corrupted, the purple emerald is unlocked without the blue one, yet at the same time you have more than seven emeralds as well.
Unfortunately you have to start a new game so that the emerald value is properly reset.
Strange, sometimes when I complete special stages there's a chance that I can get even the gray one without the need of getting the rest. Thanks for letting me know by the way.