The best way to authenticate a Rosenthal china pattern is by looking for the Rosenthal mark on the back of the china. The mark is on the bottom of a plate or tea cup. The mark design varies by the time produced but is usually a crown with a cross on top and two scepters crossing underneath with "Rosenthal" and the country of manufacture (Germany, Bavaria or U.S. Standard).
Some Rosenthal marks have the artist's name underneath the company name rather than the country of production. In the 1990s, Rosenthal partnered with Versace, so the mark has either the Versace name or the Versace name and crest above the Rosenthal mark. On occasion, the Rosenthal company name is split on either side of the crossed scepters with "Rosen" on one side and "thal" on the other. Others simply have "R." on one side of the crossed scepters and "C." on the other. Marks on pieces manufactured from 1923 to 1937, 1940 to 1942 and 1949 to 1952 use a pair of crossed roses rather than scepters. The Classic Rose collection that was produced from 1974 to 1983 also used the pair of crossed roses in the Rosenthal crest. It also featured the words "Classic Rose" either around or under the crest.