Many items of porcelain carry some type of mark on their hidden side -- that is, on the bases of cups, vases and figurines and on the undersides of plates. These marks can tell you who made a certain piece and sometimes when and where. It is partly for this reason that porcelain has become such a strong part of the collectibles market, because collectors enjoy the certainty of owning a clearly marked piece. Furthermore, carrying the mark of a sought after manufacturer can make all the difference to an item's value.
Look first for the maker's mark. This can range from an eye-catching printed design to a scarcely visible mark blind-stamped -- i.e., impressed without the aid of colour -- into the pottery. If you are struggling to read a blind-stamped mark or even to tell if a piece has one, hold a torch up against the porcelain from the other side -- this will illuminate any hidden letters. Most marks will prominently feature either a name or a set of initials, perhaps appended to a visual symbol known as a "device." To learn more about the manufacturer, simply look up the name in a reference book such as the Encyclopedia of British Pottery and Porcelain Marks by Geoffrey A. Godden. Look up initials in exactly the same manner; the guide should give you the manufacturer's name and refer you to a full entry on them.
Search next for a hand-painted monogram -- i.e., a set of initials. This will be the painter's or decorator's mark. The very presence of such a mark is interesting because it tells you that the vase's decoration has been handcrafted as opposed to applied by machine and this is a sign of prestige. By reference to a specialist guide, you might even be able to identify the individual decorator -- serious collectors of Poole pottery and Troika, for instance, take a great interest in understanding the contributions of particular artists.
Check also for an impressed monogram. This will most probably be the mark of the designer who conceived that particular pattern. These designers can become highly collectable in their own right. The firm Royal Doulton, for instance, employed a number of individually celebrated designers at their Doulton Lambeth studios. On Doulton Lambeth wares look out especially for an intertwined "GT" monogram, which stands for the highly sought after name George Tinsworth.