Pottery & Porcelain Marks – Words & Initials – J: Jacob Petit and his brother worked in the early 1800s to 1862. They made copies of Chinese Export porcelain, French dinnerware and figurines, and work by other factories. Today collectors value the "JP"-marked pieces as much as some of the ceramics that were copied. Potteries using "J" other than Jacob Petit have marks here.