Bone china is the toughest and costliest of the kinds of china called porcelain. Bone china is made from a mixture of clay and the pulverised, burnt bones of animals. When bone china is held to the light, it is translucent. It is also cooler to the touch than pottery and other porcelains. The history of English bone china goes back to Josiah Spode in the mid 1700s, and some of the markings associated with bone china are almost as old.
Check for pattern names and numbers. Bone china produced before 1810 does not have pattern names or numbers, according to the website AW Antiques and Collectibles. Therefore, no pattern names or numbers could indicate a very old piece of bone china.
Check for kite marks, which are kite-shaped emblems on the back of the china. Encoded in those marks will be the month, day and year that the china was produced. That information is not readily visible, but there are websites that can help you decipher the marks. Kite marks were used most often in the mid-1800s. After 1883, registration numbers were used. These numbers indicated the year the china was produced.
Look for the words "Royal Arms" or "Royal" in the manufacturer's name. The words "Royal Arms" were not used until after 1800. The word "Royal" was not used until after 1850.
Look for the words "Limited" or "Ltd." These marks were not required until after 1860.
Look for the country of origin in the marks on bone china. In 1891, information about the country of origin was required for goods imported into the United States.
Try first to identify the manufacturer. Many of the most popular producers of bone china include their names on the back of the china. You will see familiar names like Wedgewood, Spode, Lenox and Royal Doulton.
Look next for the words "English Bone" and "Bone China." These words usually indicate that the china is a product of the 20th century, but it may have been produced as early as 1875 if it says "Made in England," according to the AW Antiques and Collectibles website.
Look for other marks that might incorporate letters and numbers. For example, on a piece of Spode, you might find a mark reading, "F/09." The mark would mean the piece was produced in February of 1909.
Look for pattern names. Most contemporary bone china will also have the pattern name incorporated into the manufacturer's marks.
Go to the experts. Antique dealers and collectors are a wealth of information. Your local library can also be a tremendous resource for information, as well as various websites.
When you consider there are dozens of manufacturers today, and dozens more from previous centuries, it would be impossible to be familiar with all the marks on bone china. For example, one website lists over 40 pages of marks for bone china produced in the United States.