Place 3 fresh cranberries into each well of an ice cube tray. Add one thick piece of lime zest to each compartment.
In a small pitcher, stir together the pomegranate juice, water (sparkling or still), and the juice of 1 lime.
Pour the juice mixture into each ice cube tray well, leaving a small amount of room at the top for expansion during freezing.
Freeze overnight or until completely solid.
Add 4–5 pomegranate cranberry ice cubes to a glass. Pour in ¼ cup cranberry juice, then top the rest of the way with sparkling water.
Finish with a sprig of fresh rosemary and enjoy immediately.