A Collector’s Guide to Signed Jewelry

F or jewelry collectors, buying a piece of jewelry that has been signed by the designer or the house that created it is a no-brainer. As the name suggests, a signature or brand indicates that that piece is an authentic product of a maison, conferring prestige and provenance accordingly.

That’s not to say that unsigned jewels don’t have value, but if you’re looking for a piece with history, one that might even be an iconic or historically significant design, it’s time to invest in a signed piece of jewelry.

Hallmarking has been a common practice in jewelry making for centuries. Since the 1300s, silver and gold standards have required that precious metals be tested and marked to ensure quality and indicate purity as a form of consumer protection. Turn any piece over, and you’ll often find a series of stamps that will tell you the exact city and year in which the piece was produced.

However, signing jewelry with a brand or design name didn’t emerge as a standard practice until the second half of the 19th century, coinciding with the founding of the great jewelry houses of today – Cartier, Tiffany & Co., Van Cleef & Arpels, and Bvlgari among them – which were largely established between the mid-1800s and early 1900s. René Lalique, who started his career as a jeweler before transitioning to the sculptural glass objects for which the brand is most renowned today, was one of the first artist jewelers to add his mark to the underside of the pieces he created.

“Historic jeweled heirlooms that can be traced back to the client they were made for, offer a glamorous glimpse into the past and a bygone era,” says Emily Barber, Senior Director and Head of Fine Jewelry at Sotheby’s. “A prime example of a notable unsigned jewel is the magnificent 18th century Anglesey Diamond Necklace sold by Sotheby’s in 2024.”

The Arts & Crafts (1860-1920) and Art Nouveau (1890-1910) movements both emerged in part in reaction to perceived defaults in the decorative arts trends of the day – namely a decline in quality and artistry, respectively. Art Nouveau in particular signaled a return to flowing shapes and organic inspiration and was incredibly popular in Paris which broadly adopted the aesthetic throughout the city.

Practitioners of the movement looked to break down the barriers between fine and applied arts. For the jewelry world, signing a piece, a practice long used by painters and sculptors, brought the jewelry industry more in line with the art world. A signature also lets a consumer know that a piece is an authentic production of a particular house, assuring clients of quality.

Signatures allow experts to accurately authenticate pieces and place them in time. The Cartier signature, for example, has changed significantly over time so a vintage piece may be marked very differently from a modern jewel.

Signatures may also exponentially increase the value of a vintage piece, but not always. Certain brands have been so prolific that mass-produced pieces will not change in value regardless of whether they have a signature. However, if you come upon a historically significant piece with a signature, the value can skyrocket accordingly. “An intact signed jewel, especially if it’s from a famed period of production or design, such as the Art Deco period, is a rare and wearable work of art,” says Barber.

Our experts are trained to identify and authenticate signatures. Copycats do exist, of course, but brand guides and serial numbers allow appraisers to accurately assess each piece. “Always refer to an expert or jewelry specialist,” Barber advises. “They can check the condition and that the jewel has not been altered.”

“Things to consider are authenticity, the design of the jewel and the date of manufacture,” says Barber. “Some designs and styles are scarcer and rarer than others. The quantity in which the jewel was made is an important factor too as some signed jewels are made several times over whereas others are created in limited editions or are unique.”

Jewels from the Art Deco period may never go out of style. Some of the most iconic pieces of all time emerged from this movement. Jaeger-Le Coultre’s Reverso timepiece, designed to withstand the rigors of polo matches, and Cartier’s Tutti Frutti collection are endlessly collectible and super valuable examples from the era. Other brands that were prolific during this era like Lacloche Freres, Vacheron Constantin, Van Cleef & Arpels, and Tiffany & Co. benefit from signatures.

Over the years, Sotheby’s has seen several significant pieces pass through our halls. Examples include a circa 1930s tie-necklace by Van Cleef & Arpels, an incredibly rare style that was sold for US$3.6 million in 2024, tripling its high estimate. A string of 73 natural pearls with a diamond clasp by Tiffany & Co. was sold the same year and ranks as one of the most expensive Tiffany pieces ever sold by Sotheby’s. In 2020, a circa-1930 Tutti Frutti bracelet by Cartier achieving US$1.34 million broke auction records for a piece of jewelry sold online.