Traditionally, the base was the dominant decorative element for most shisha pipes. Most are made of glass (typically blue or green). Since modern tools make it possible to create ornate stems from metals other than gold, there is a growing trend to match them with metal bases. If you are shopping for a replacement base, keep in mind that the size of the opening is what's most critical. If it's too small it just won't work with the stem, and if it's too large it can be difficult to make the pipe stable.