You'll need to open the dolls by linking them with Charms of the same color.
There are dolls of several sizes. When they are bigger than a Charm, they contain two smaller dolls that need to be linked as well. The smallest dolls have a Diamond inside that you'll need to find.
Dolls can also be destroyed through the explosions/Rays created by the Blasts or with the help of Birds.
In this game mode, it is not necessary to bring the Diamonds to the Necklace.