Q This set belonged to my mother when she was a child living in Vancouver, British Columbia, around the 1930s. The only markings show “Made in Japan.” The plate is 5 inches across, the saucer 3 ½ inches. I have not been able to find any like this online. When might it have been made?

A In Ancient Greek mythology, Iris was a messenger of the gods, the embodiment of rainbows. Named after her, iridescent surfaces have been prized since ancient times for their reflective properties. Whether on ceramic, metal or glass, light shining on these surfaces diffuses into a number of colors, making spaces look larger and brightening dark rooms.

Examples of iridescent glass have been found in excavations of ancient Roman and Islamic sites. In the 18th and 19th centuries, European and British potteries concocted glazes of metallic oxides that gave the same luminescence to their goods. Well into the 20th century, Tiffany’s Favrile and Steuben’s Aurene glass were highly prized for their refracting surfaces.

Your charming tea set with its iridescence is what is commonly called Lustreware. After painting and decorating, the pieces are glazed with a transparent metallic finish and fired again to produce the illusion of luminescence.

The Japanese Morimura brothers popularized it in the 1870s. Japan had been open to trade with the West for only a few decades when entrepreneurs Ichizaemon and Toyo Morimura developed products suited to the American market.

With offices in Tokyo and New York City, Morimura imported and sold items — especially inexpensive porcelains — being made by other companies. After a visit to the St. Louis World’s Fair in 1904, the brothers decided to cut out the middleman. They opened their own porcelain factory in the Noritake region of Japan, producing and decorating their own blanks as well as selling blanks to other decorators.

A profitable product was a line they called Lustreware, painting their blanks with a metallic oxide glaze to imitate the surface of gold or silver. The glazes were so popular that the company developed a variety of colors, decorative decals and hand-painted scenes; they added pieces to their services — coffee pots, cheese domes — not normally seen in Japanese sets.

Although popularized by the Morimuras, lines of tableware with a lustrous glaze were produced by porcelain factories all over Japan. According to www.gothenborg.com, the tourism industry of Japan even published a guide, “Some Suggestions for Souvenir Seekers” identifying regions and factories where these goods were being made.

Lots of this Japanese-produced porcelain is lumped together as “Nippon” or “Noritake,” but neither of those terms identifies the maker. Nippon is the Japanese term for Japan, used after the McKinley tariff act of 1891 mandated imported items be marked with the country of origin. Noritake is the town (like Limoges in France) where the bulk of this manufacturing happened.

Due to fluctuating U.S. tax laws, we can date the production of your mother’s tea set to between 1921 and 1941, because in 1921, tax laws were updated to require products be labeled in English as “Made in Japan.” During and after WWII, most Japanese nonmilitary production halted; from about 1945 to 1952, when the U.S. was helping to rebuild Japan, export pieces were marked “Made in Occupied Japan.”

My New England grandmother’s set was reserved for special occasions and thus survived complete and in good condition. We broke up the set so that several of us could have pieces for remembrance.

Your set was made for a child, so fewer of them survive intact. Depending on completeness, your set could be worth $40 to $70. Bring it out for Thanksgiving dinner!

Jane Alexiadis is a personal property appraiser. Send questions to [email protected].