What currency do Smurfs use?

Could you enlighten me on the curious matter of the financial system within the world of Smurfs? Specifically, I'm intrigued to know what currency these charming blue creatures utilize in their daily transactions and economic endeavors. Do they possess a unique form of money, or do they rely on some form of bartering system, or perhaps even adopt a currency used by their human counterparts in the realm of folklore and children's literature?