The carat for Au foil used for restorations is:

Direct filling gold, also called gold foil, is a metallic restorative material that relies on its ductility and malleability to adapt to a cavity preparation. The restorative process requires condensation that makes the final restoration practically a wrought metal. KARAT It refers to the parts of pure gold present in 24 parts of alloy, e.g., — 24 karat gold is pure gold. — 22 karat gold is 22 parts pure gold and 2 parts of other metal.