Q: This porcelain relief, which I have learned is called a "phanolith," has been in our family for over 100 years. It's signed "Jean-Baptiste Stahl" in the bottom left corner. The frame measures 23 3/4 inches wide by 10 3/4 inches high. What is it worth?

A: "Phanolith" is the name of a porcelain relief technique developed by Jean-Baptiste Stahl (1869-1932) when he was head of the modeling department at Villeroy & Boch in Mettlach, Germany. The white relief design, much like the pate-sur-pate method, is made by painting layers of slip on a blue or green background. Stahl won a gold medal when porcelain decorated using his new technique was first displayed at the 1900 World's Fair in Paris. Other designers later made plaques with similar decoration. Stahl's Mettlach phanolith plaques can sell for $400 or more, depending on condition.