Tweezers:

When you use this booster, you can choose one bead to destroy and remove from the board.

Cross Medallion:

When you use this booster, you choose a bead on the board, and the Cross Medallion removes the row and column that intersect at that bead, in a cross shape.

You can acquire more of these boosters in exchange for diamonds by tapping their icons when you have none left. You can also get more via Daily Rewards, Blitz Offers, and assembling certain local mementos.