Taking the Mystery Out of Identifying Antiques

QUESTION: I have what I believe to be an English ceramic plate with a mark that looks like a diamond with a bunch of letters and numbers in it. Can you tell me what that means?

ANSWER: The stamp on the back of your plate is known as a mark. Manufacturers of English pottery used this particular design between 1842 and 1883. The letters and numbers indicate the dates of the plate’s design registration with the British patent office. You can easily decipher this alpha-numeric code by checking the chart found on the Phoenix Masonry Web site or in Kovels' New Dictionary of Marks--Pottery & Porcelain: 1850 to the Present by Ralph and Terry Kovel (Crown Publishers, New York).

Pottery makers replaced this diamond-shaped registry mark with a sequential numbering system prefaced by the abbreviation Rd. No.  in 1884. Over the years, they modified the arrangement of the numbers several times, so it can be confusing. If you need specific information, you can contact the British Designs Registry Patent Office for dates registered in and after 1909 and the British Public Record Office for dates registered prior to 1909.

Sometimes, pottery and porcelain makers used word indications that spelled out the date. If the mark shows the country of origin, this means the piece dates after 1891, according to the U.S.  McKinley Tariff Law.

Often manufacturers worldwide employed words to describe their wares. These usually had start and end dates, making it easy to figure out the approximate date of a piece. For instance, the term "Nippon,” the Japanese name for Japan, indicates that piece of Japanese porcelain dates from 1891 to 1921while "Made in Occupied Japan" shows that the piece dates from  1945 to 1952. "Semi-vitreous" means the piece appeared on the market after 1901 while "bone china" indicates that the piece dates generally from the 20th century.  The phrase "oven-proof' appeared on pottery and china after 1933, but "dishwasher proof ” didn’t appear until after 1955. Sometimes a location, such as "East Germany" can indicate a time period, which in this case extends from 1949 to1990.

If a piece of pottery or porcelain has a mark showing a design and/or maker’s name, this information may also help to date it. You’ll find loads of resources, both in print and online, to help you identify early English, European, and Asian pottery and porcelain marks.

In the United States, makers stamped patent numbers on the backs and bottoms of their pottery pieces. A patent number represents the very earliest an article could have been produced. For example, a patent number of 16,388 indicates the piece appeared after Jan. 1, 1857 but prior to Jan. 1, 1858. Therefore, it dates from 1857, the year of its patent registration. Should you discover several sequential patent number sets on one piece, you should look up the final set on a patent date chart to date the piece.

Marks on furniture, glass, and silver are another story. When a maker uses his name or logo, you may have enough information to track the date of manufacture. Often during the course of the run of a piece, the maker will use different names. This is true of Tiffany glass. On some pieces, Tiffany signed, that is incised, his name “Louis C. Tiffany.” On later pieces, “Tiffany Studios” appears on the piece, and yet others show no mark at all.

Early furniture makers often scratched their name on the bottom of a piece, such as under the seat of a chair. But by the early 20th century, almost all manufacturers used labels affixed to the backs or bottoms of their pieces. If a piece of furniture has a label, it surely indicates that the piece is modern. Gustav Stickley employed a red decal featuring his logo, a joiner's compass, from 1902 to 1903 as compared to the revised decals Stickley used between 1903 and 1912.