In Pokemon Shuffle, I used a Jewel to replenish 5 hearts. But instead of doing that, it just added 5 to the number beside the heart count! What's up with that?
Note: latest update.
No need to worry. I believe they did that to keep purchased hearts and regular hearts separated. Why? I don't know. They still work like normal hearts, so there's no need to worry.
Source: experience and buying 5 hearts with a jewel myself