The Grueby Faience and the Grueby Pottery both were very consistent with their marking system. It began with simple block letters, but quickly included the flower symbol once it was trademarked. These markings were die-stamped into the bases, although sometimes the angle of the stamp left only partial marks. Additionally, it was not unusual on later pieces for the glaze dripping and pooling on the base to partially obscure the marks. Later pieces often included a paper label in addition to the stamped marks, but most of these labels are long lost.

Artist marks, initials, and ciphers are often found on the bases as well. The employees involved with the creation of these works were considered craftsmen, and encouraged to sign their work. Additionally, worker output (and pay) was tied to the number of pieces signed by them. Only around a dozen of the artists names are documented today.

Below are some images of the marks used by the Grueby Pottery and Grueby Faience.