A trademark indicates the age of a porcelain piece, as well as the manufacturer, both important for determining the value. Websites such as Antique Marks provide free PDF downloads of trademark lists that help collectors date their items. Manufacturers, such as Lladro, also have trademark information online.
Porcelain imported into the United States after 1890 was required to have the country of origin included in the trademark. When the name is missing, the manufacturer's mark helps determine origin as well as age.
For example, using the Lladro website, a collector can find an assortment of trademark designs. Some just have the name while others include "Made in Spain" and/or a symbol. Newer porcelain may also carry a manufacturing date, as seen in the examples from 1978 and 1996. Newer Lladro trademarks also carry the copyright sign.
English pieces are also easily dated by markings. The word "trademark" wasn't used until 1855. The symbol for limited (LTD) wasn't used until 1880. If a collector has a piece with the word trademark but without the LTD, the date window is narrowed to a 25-year period. By comparing the marks with a manufacturer's list, such as for the Wedgwood brand, collectors can date both older and newer pieces.