During the 1800s, much of the world's finest porcelain came from England, France and Germany. Companies such as Meissen and Rosenthal in Germany and Havilland and Sevres in France became famous for beautiful, ornate designs, while the Staffordshire region of England gave birth to legendary companies such as Wedgwood, Royal Doulton, Spode and Minton. According to the Lenox China Company, its entrance into the market in 1889 helped the U.S. porcelain industry to rival these European companies. The great porcelain manufacturers of the era usually marked their products with the company's name, initials or trademark symbols.
Gently turn the cup over to find the maker’s mark, stamped in ink on the bottom. Stamps are often worn and faded from age and many washings, so the mark may be difficult to read. Reference books such as “Antique Porcelain” by John Sandon will help in identifying company symbols, trademarks, names and abbreviations, and will also help identify china patterns and assist in dating the cup.
Look for a country of origin. Sometimes, but not always, pieces stamped with a country of origin will be made after 1891, the year that U.S. trade laws required imports to be marked with the country of manufacture. Likewise, check the wording. According to Mike Wilcox of Wilcox & Hall Appraisals, the word “trademark” indicates a post-1862 manufacture date, while the words “limited” or “LTD” indicate a manufacture date after 1860.
Look at the color of the mark. Wilcox states that manufacturers stamped their pieces prior to firing, and the only pigments that could withstand these high temperatures were iron red and cobalt blue. Prior to 1850, blue stamping was more popular with manufacturers than red. However, be aware this is only a very general rule of thumb, and works best when used in conjunction with other dating methods for the piece.
Look at the shape of the handle. Expert and dealer Paul Mould writes on his "Antique Porcelain Collector" website that cup handles became more ornate as the 1800s progressed, so simpler handles may indicate an earlier date. Additionally, Mould says, if the cup has a matching saucer, a deeper, bowl-like design without a center “recess” for the cup indicates a pre-1830s piece.