Marx & Gutherz Fish Plates

Q How would can I find the value on a set of Marx & Gutherz fish plates? They are marked with circular red mark that says, ”Marx & Gutherz, Carlsbad.”

A Maximilian Marx and Oscar Gutherz began working together in Altrohlau, Bohemia (now Stara Role, Czech Republic) about 1876. The company was financed by Lazarus Straus & Sons, an importer in New York City. Marx sold his interest in the company to Oscar’s brother, Edgar, in 1898 and the company name became Oscar & Edgar Gutherz. Porcelain production began, and both decorated and undecorated wares were exported to the United States. This mark was used from 1876 until about 1889. Value of a fish plate and 12 plates is about $750 depending on appeal of the design.