After using a purchased Necklace of Fireballs with 8 initial rounds, it was great as it allowed my non Magic fighter to be able to cast an offensive area effect blast. I had assumed that the device would recharge with resting. However, after rest, it didn't reload itself at all. Is there any way to recharge this amulet?

Thanks

ADDENDUM: Nevermind. I had one charge left and used it, thereafter the amulet just disappeared, so I guess it's only intended as a finite use item; sad.