Cartier Opal Tiara Headlines Sotheby’s Royal and Noble Jewels

Two tiaras, two centuries and two very different family stories will share a single evening in Geneva. On 11 November, Sotheby’s brings its Royal & Noble Jewels sale to the city’s autumn auction week, led by a 1937 Cartier black opal and diamond tiara worn at the 1953 coronation and a Mellerio diamond tiara that spent most of a century out of public view.

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What is in Sotheby’s Royal & Noble Jewels sale?

Royal & Noble Jewels is Sotheby’s dedicated Geneva sale for jewels with documented aristocratic or royal provenance. The house presents the 2026 edition as a continuation of its single-owner sales of the jewels of the Bourbon Parma family and “Vienna 1900: An Imperial and Royal Collection,” and notes that its last three editions sold every lot.

The eight highlights released so far read like a short course in twentieth-century taste. Beyond the two tiaras, there is an Adler | Bucherer necklace of sapphire, cultured pearl, mother-of-pearl and diamonds centred on a 43.07-carat octagonal sapphire; a ring pairing a 7.83-carat cabochon sapphire with a 6.77-carat emerald, once owned by Catherine, Lady Walston; and two Bulgari pieces from an Italian noble family, a ruby and diamond bracelet and a ring with a 7.89-carat emerald. An antique emerald and diamond bangle, centred on a 27.38-carat cabochon emerald, and a matching brooch carry a lineage that runs through Queen Amélie of Portugal, according to The Royal Watcher’s lot-by-lot listing.

The sale has been touring: the highlights were shown in Zurich from 12 to 23 October and in Singapore from 22 to 25 October, and Galerie magazine placed both tiaras among its seven pieces to follow during the November Geneva sales. For context on the rest of the week, see our previews of the Bulgari Pink at Christie’s Geneva and the Phillips Geneva Jewels auction.

Why is the Devonshire Cartier opal tiara so important?

The story begins with a royal tour. In 1936 and 1937, Edward Cavendish, then Marquess of Hartington, and his wife Mary travelled through Australia and New Zealand, and the black opals at the heart of this jewel were presented to the couple during that journey, as Jewellery World reports. In 1937, the coronation year of George VI, the opals went to Cartier, which set them in platinum with diamonds in a crisp Art Deco design.

What makes it a collector’s jewel rather than a museum piece is its versatility. It can be worn on a frame as a tiara or as a necklace, and five opal and diamond elements detach as clip brooches, so the same jewel can dress a state occasion or a lapel. Mary Cavendish, by then the Dowager Duchess of Devonshire, wore it as a necklace at Queen Elizabeth II’s coronation in June 1953, where she served as the senior lady of the Queen’s household, a role she held until 1967, according to The Court Jeweller.

It has also had an unusually public two years for a family jewel. It appeared in the Victoria and Albert Museum’s 2025 Cartier exhibition, and in February 2026 Sotheby’s lent it to director Emerald Fennell for the London premiere of Wuthering Heights, which the auction house described as its first public wearing in more than 70 years. The tiara has remained in the Cavendish family for close to nine decades, The Court Jeweller’s newsletter notes.

A tiara that becomes a necklace and then five brooches is not a relic. It is a wardrobe in platinum.

What is the story of the Mellerio Orléans tiara?

The second tiara is older and quieter in design. Made around 1862 by Mellerio dits Meller for the London International Exhibition of that year, it is a diamond bandeau of old mine-cut and rose-cut diamonds arranged in a Greek key meander, a Greek revival look that Town & Country links to Napoleon III’s purchase of the Campana collection of antiquities for the Louvre. Like the Cartier, it converts to a necklace.

Antoine d’Orléans, Duke of Montpensier, bought it two years after the exhibition and gave it to his eldest daughter, Marie Isabelle, for her 1864 marriage to Philippe d’Orléans, Count of Paris. It later passed to her younger son, Ferdinand, Duke of Montpensier, and then to his widow. After her death in 1957 the tiara slipped from view for most of a century before resurfacing in a private collection, which is where its Geneva estimate begins.

A short history of the tiara at auction

The two tiaras bracket the great age of the form. Mellerio, which traces its lineage in Paris to 1613 and is among the oldest family jewelry houses in Europe, made its piece in the decade when Second Empire court life made the diamond bandeau essential evening wear. Cartier’s opal tiara belongs to the final flourish, the 1930s, when coronations, court presentations and state dinners still called for one, and when Art Deco designers favoured convertible jewels that could be taken apart and worn in daylight.

Black opal is the more unusual material here. Most precious opal shows its colour against a pale body; black opal, found chiefly in New South Wales, shows it against a dark one, which makes the play of colour look deeper and more saturated. Major houses set it only occasionally, and a documented Art Deco Cartier piece built around Australian black opals with a coronation record is, in our view, close to unique. Since the middle of the twentieth century, as fewer families have had occasions to wear them, tiaras have moved steadily from the vault to the saleroom, and Geneva has become their natural stage. We followed a similar imperial thread this weekend with the Tsar Alexander I pendant heading to Elmwood’s.

For the Collector

• Estimates and fees: The Cartier tiara is reported at CHF 780,000 to 1.1 million and the Mellerio at CHF 300,000 to 500,000. Auction estimates generally exclude the buyer’s premium and taxes, so confirm the final terms on Sotheby’s sale page before bidding.
• Where to see them: The full sale is on view at the Mandarin Oriental, Geneva, from 6 to 10 November, and condition reports can be requested from the specialists in advance.
• What drives value: An unbroken, documented provenance, the maker’s signature, original fittings for each way of wearing a convertible piece, and photographic records such as the 1953 coronation all carry weight with bidders.
• What to check with opals: Opal is softer than sapphire or diamond and can be sensitive to sudden temperature changes and very dry conditions, so ask about the condition of each stone and any past repairs.
• A note on results: Past auction prices for royal jewels do not predict future value, and a jewel with this kind of story is best bought for love and history first.

Frequently asked questions

When is Sotheby’s Royal & Noble Jewels sale in 2026?

The sale takes place in Geneva on 11 November 2026, with a public viewing at the Mandarin Oriental from 6 to 10 November.

How much is the Devonshire Cartier opal tiara estimated at?

It is reported at CHF 780,000 to 1.1 million, about $944,000 to $1.33 million, before the buyer’s premium.

Who wore the Cartier opal tiara at the 1953 coronation?

Mary Cavendish, Dowager Duchess of Devonshire and senior lady of Queen Elizabeth II’s household, wore it as a necklace at the coronation in June 1953.

Can the Mellerio tiara be worn as a necklace?

Yes. The circa 1862 Mellerio diamond bandeau converts into a necklace, like many tiaras of its period.

Sources: Sotheby’s · Galerie · The Court Jeweller (newsletter) · The Court Jeweller · Jewellery World · Town & Country via AOL · The Royal Watcher