Judith Price checks out jewelry auctions all the time, looking for the beautiful, the bargains, the surprises.

She found all three in a Christie’s online auction in December. “The auction was 99.9 percent jewelry,” said Ms. Price, the president of the nonprofit National Jewelry Institute in Paris. But one piece stood out: an antique watch brooch, designed to be pinned on a lapel or bodice.

Mafalda Chenu, a Christie’s jewelry specialist, said the auction house put the piece in the auction because “it’s definitely a watch but also nicely set with diamonds. We thought it would be lovely for a lady to wear.”

Few, if any, watch brooches are made today, but in the 18th and 19th centuries, before the wristwatch was invented, they were common, Ms. Chenu said. “Men had pocket watches, and women had watch pendants and brooches.”

The Christie’s listing described the brooch as having a “white dial surrounded by rose-cut diamonds with gold hands and black Arabic and Roman numerals, the open case back showing the gilt skeletonized manual movement with pierced foliate balance cock, late 18th century, 33 cm diameter. Signed Abraham Colomby.”

It continued: “Born in 1702, Abraham Colomby (also known as Collomb, Colombi and Colomb) was a Swiss watchmaker and retailer who came from a famous watchmaking family in Geneva. Abraham Colomby died in Geneva in 1776 after having flooded Europe with his creations.”

Colomby’s signature style prompted Ms. Price to bid. “I love the bow, and I’m not really a bow person,” she said. “The other thing that attracted me was its history.” The date of Colomby’s death, 1776, “marks the beginning of our country’s independence. I thought, ‘I can buy a piece of history.’”

The watch does not work, but Ms. Price said that was fine. “I can get it working again but I’m not going to. I have the key to have it done. But then you have to wind it,” she explained, adding that she is content to wear it as a piece of jewelry.

Christie’s estimate was 600 to 800 euros ($683 to $910). Ms. Price waited until the auction’s last day to place her bid of €1,200, and won it. With the commission, the total cost was €1,500.

“Mafalda told me I got a real bargain,” Ms. Price said. “Some people buy books to get a taste of history. I bought a brooch.”