Slag glass resembles a marble cake. It can be streaked with different colors. There were many types made from about 1880. Caramel slag is the incorrect name for chocolate glass made by Imperial Glass. Pink slag was an American product made by Harry Bastow and Thomas E.A. Dugan at Indiana, Pennsylvania, about 1900. Purple and blue slag were made in American and English factories in the 1880s. Red slag is a very late Victorian and twentieth-century glass. Other colors are known but are of less importance to the collector. New versions of chocolate glass and colored slag glass have been made.