Bandgaps　of　photoluminescent　graphene　quantum　dots　(GQDs)　synthesized　from　anthracite　have　been　engineered　by　controlling　the　size　of　GQDs　in　two　ways:　either　chemical　oxidative　treatment　and　separation　by　cross-flow　ultrafiltration,　or　by　a　facile　one-step　chemical　synthesis　using　successively　higher　temperatures　to　render　smaller　GQDs.　Using　these　methods,　GQDs　were　synthesized　with　tailored　sizes　and　bandgaps.　The　GQDs　emit　light　from　blue-green　(2.9　eV)　to　orange-red　(2.05　eV),　depending　on　size,　functionalities　and　defects.　These　findings　provide　a　deeper　insight　into　the　nature　of　coal-derived　GQDs　and　demonstrate　a　scalable　method　for　production　of　GQDs　with　the　desired　bandgaps.