The Jewel Box is a magical item from Jewelpet Happiness.
History
The box was made by Jewelina, who presented it in episode 1, where it was given to Ruby so she and her fellow Jewelpets could fill it with Magic Gems.
When a certain number of Magic Gems is obtained, the box expands with more slots and releases a magical aura that upgrades the Jewelpet Café Happiness.
The box is almost always on an animated nightstand in the Café.