There are a wide variety of sizes, styles and colors of marbles that are valued by antique collectors. A pontil mark indicates a hand blown marble. There are lots of reproductions the in the marble area, so beware and perhaps enlist the help of a friend who knows marbles well on your first excursions to find these lovely treasures. Everett Grist, author of Antiques and Collectible Marbles , defines marble quality as one of three levels.
Sulphides are by far the most popular type of marble now.
These characters are usually animals or small figures of people. Cloud marbles have several layers to them, the inner layer is shaped like a hot air balloon with cloudlike puffs of color floating around it, the outer layer is tranparent or lightly colored glass. Comic marbles were made in the 1920s by a company in Illinois. The Pelitier Company stamped the marbles with comic characters and then covered them with a layer of glass. Clay marbles are sometimes painted with china or other decorative-style designs.