Is it permissible to work in selling charcoal to restaurants that serve alcohol on their drink menus?

There is no harm in selling charcoal to restaurants that serve alcoholic beverages, unless the seller is certain that the charcoal will be used for an unlawful purpose, such as grilling pork or placing it in a hookah. In such a case, it is not permissible to sell it to someone who intends to use it for an unlawful purpose.