Last year, a man attended a yard sale in New Haven, Connecticut, and forked over $35 for a white porcelain bowl patterned with blue flowers. That price might seem a little steep to seasoned yard salers—the bowl’s diameter is only about 6 inches—but the buyer didn’t even try to haggle.

Thinking the item might be worth much more than that, he emailed photos to Sotheby’s. Angela McAteer and Hang Yin, the resident experts on Chinese artifacts, were practically awestruck. “It was immediately apparent to both of us that we were looking at something really very, very special,” McAteer told AP News. “The style of painting, the shape of the bowl, even just the color of the blue is quite characteristic of that early, early 15th-century period of porcelain.”

A quatrefoil surrounded by florets, leaves, and other motifs.Sotheby's

A thorough in-person evaluation supported their theory. McAteer and Yin believe the bowl was created for the court of the Ming dynasty’s third emperor, known as the Yongle Emperor, who ruled over China from 1403 to 1424. His reign was marked by an imperial commitment to perfecting porcelain craftsmanship. “The Yongle Emperor really promoted the artistic importance of porcelain,” McAteer told CNN. “He elevated it from being a utilitarian bowl, for example, into a true work of art.”

But while the production techniques influenced potters for centuries to come, the pieces themselves are rare. The bowl recently found in Connecticut is one of only seven of its kind (that we know of), almost all of which are kept in museums. They’re known as “lotus bowls,” for their lotus-bud shape; and the shape of the ring attached to the bottom of the bowl for stability is called jixin, or “chicken heart.” This particular artifact features cobalt blue blossoms of lotuses, peonies, chrysanthemums, and pomegranates, among other designs.

Sotheby’s is selling the bowl as part of its “Important Chinese Art” auction on March 17. How much the lucky yard saler—who has decided to stay anonymous—stands to earn remains to be seen, but the antique is estimated to fetch anywhere from $300,000 to $500,000.

[h/t AP News]