Confirm with version 1.5.8, works perfectly.
It's the key to hack the in-stage values and not total gem count as the latter is stored encoded. I found it only after long and numerous fuzzy searches. Even then all I could do was freezing the values. Alas, after some orders these values just stopped working. So don't waste your time and hack in-stage values.
Tip: this cheat kinda ruines the game making it too easy, so I advice to use it only for revealing some battle stages where you could earn plenty of gems (1st "mobs free-walking" stage gives 110-200 gems).
