Sotheby’s Royal & Noble Jewels sale in Geneva on Wednesday, November 12, 2025, brought together treasures that showcased both exceptional craftsmanship and the deep, layered histories of the families who once wore them.
Leading the auction was an historically important natural pearl and diamond convertible jewel — the highest-selling lot of the day — a rare 1840s survivor of the Romantic period’s extravagant face-framing hair ornaments.
Adding to the narrative of glamorous dynasties was the jeweled collection from Neslishah Sultan, the last Ottoman princess. Her life bridged the final chapters of both the Ottoman Empire and Egypt’s Mohammed Ali dynasty. The collection (Lots 601–621), including the “magnificent and historical light pink diamond and diamond ring,” was passed down through exile and new beginnings. (The ring is impressive, featuring a 13-carat light pink Old Mine cut. – see below)
Tiaras
And naturally, no Royal & Noble Jewels sale feels complete without tiaras, those brilliant symbols of ceremonies, romances, and fairytales.
This year’s array ranged from a garland of wild diamond roses, once owned by the Duchess of Portland, to an 18th-century flower garden (Lot 662), from the Barons Gisborough, with close to 60 carats of diamonds. Each tiara is a nod to the kind of evenings these pieces were made for… the court balls, formal receptions, and all the sparkle that went with them.
Napoleon
Also included in this auction were two historically significant Napoleonic jewels from the Hohenzollern Treasury: a diamond-encrusted brooch/pendant identified as a hat ornament Napoleon left behind in his carriage while fleeing the battlefield at Waterloo — you remember his sideways hat*, yes? — and a large and unique 132.66-carat “green beryl,” believed to have been worn at his 1804 coronation.
Both Napoleon brooches remained with the Prussian royal family for over two centuries, joining the Hohenzollern treasury after the death of Queen Elisabeth Ludovika of Bavaria in 1873. These two pieces added an interesting historical thread to the sale — artifacts as much as pretty jewels, tying the auction to the political dramas of the Napoleonic era.
From the gemological side, we will of course delve into the differences between “green beryl,” “emerald,” and “aquamarine,” as this may have influenced its astonishing hammer price of 838,200 CHF — roughly 17 times higher than its high estimate of 48,000 CHF.
Jewels Underestimated
Several jewels, like the green beryl, sold for far more than anyone anticipated. There was an 1880 crescent moon diamond brooch, with 6 to 7 carats of diamonds, estimated to sell for 6,000 CHF, that sold for 33,000, over 5 times the high estimate. A 1940s diamond necklace, with approximately 35 carats of diamonds, estimated at 10,000 CHF, sold for 40,640 – 4 times the high estimate! And that 13-carat light pink diamond ring (noted above), estimated at 400,000 CHF, sold for 2,917,000 CHF!
Now let’s take a closer look at some of the very important historical royal and noble jewels at this year’s auction.
Rare and Historically Important Natural Pearl and Diamond Jewel and a Brooch
For anyone who thinks “convertible jewelry” is a modern invention, this piece offers a gentle correction. Dated circa 1840, it comes with so many fittings and possibilities that it’s essentially the Swiss Army Knife of natural pearl and diamond jewels… elegant, adaptable, and brilliantly over-engineered. And it sold for close to $450,000 USD!
Estimate: 340,000 – 500,000 CHF
Sold: 355,600 CHF
This jewel is an object lesson in convertible jewelry.
At first glance, it is a diamond and pearl garland necklace. But it is designed so that each section can be detached and re-assembled into something else. First, if you simply unclasp the necklace in the front, it becomes a head ornament… worn as a headpiece, it sits like an open coronet, draping across the top of the head, just above the forehead, then sweeping down behind the ears in a curve of diamond-set vines. The entire jewel is set with flowers of old mine- and rose-cut diamonds, with suspended natural pearl drops.
Every vine element can be separated and refitted thanks to the original assortment of 19th-century fittings, which include connectors, brooch backs, hairpins, and dedicated tiara mounts. Some pieces have been adapted over time, as often happens with jewels of this period, but the overall concept… a very clever necklace that becomes a head jewel, a series of brooches, or even hair ornaments, remains intact
The Main Brooch
The accompanying brooch, shaped as a diamond ribbon, centers a 15 mm button-shaped natural pearl and supports three elongated natural pearl drops capped in rose-cut diamonds. It dates slightly later (1860) but matches beautifully with the main jewel.
Natural Pearls
The necklace features drop-shaped and slightly baroque drop-shaped natural pearls measuring from approximately 12.39 – 12.57 x 18.03mm to approximately 5.95 – 6.65 x 7.65mm
The necklace has been dated circa 1840 with later alterations for different uses.
Gem Lab Report: The pieces are accompanied by several SSEF reports, all stating that the pearls are of natural salt water origin.
A Superb Emerald and Diamond Pendent Necklace, by Cartier
Estimate: 300,000 – 500,000 CHF
Sold: 1,331,000 CHF ($1.66 million USD)
This 1932 Cartier necklace is a masterclass in geometric Art Deco design.
Its centerpiece pendant is an 11.78-carat octagonal step-cut Colombian emerald, suspended and swinging freely inside an octagonal surround of Old European Cut diamonds. From there, the necklace settles into a geometric triangle: a 5.54-carat marquise serves as the keystone uniting the left and right diamond strands, while a 3.12-carat heart forms the triangle’s tip — a deliberate visual cue leading the eye straight to the emerald and diamond pendant.
And in true Cartier fashion, the clasp is no afterthought: it holds a 2.64-carat cushion-shaped emerald wrapped in rose-cut diamonds. Just as special, this 1930s Art Deco necklace comes with its original fitted Cartier case.
Gem Lab Report: Accompanied by SSEF report no. 149269, dated 9 October 2025, stating that the emerald is of Colombian origin, with a minor amount of oil in fissures, together with an appendix letter; further accompanied by GIA report no. 2235741213, dated 9 October 2025, stating that the marquise diamond weighing 5.54 carats is D Colour, VS2 Clarity, together with a type IIb classification letter.
Magnificent and Historical Light Pink Diamond and Diamond Ring
Here we have this prominent Light Pink Old Mine Cut diamond weighing 13.86 carats, mounted in rose gold and embellished with Old Mine- and Rose-cut diamonds, circa mid-19th century. The diamond is stunning and hard to miss — so much so that you’ll almost miss the mounting.
Estimate: 240,000 – 400,000 CHF
Sold: 2,917,000 CHF (approximately $3.6 million)
Gem Lab Report: The diamond is accompanied by GIA report no. 2235670621, dated 26 August 2025, stating that the diamond is Light Pink*, Natural Colour, and VS2 Clarity.
*Light Pink: Just a reminder that the color grade of “Light Pink” is not in the Fancy color grade range. As a comparison, the “Light” grade range is in the comparable yellow S to Z alphabetical range. One note here: The larger the diamond, the more apparent the color.
The ring comes with royal provenance:
Empress Catherine I of Russia (1684-1727)
Sultan Ahmed III (1663-1736)
Sultan Abdul Hamid II (1842-1918)
Princess Emina Ilhamy (1858-1931)
Princess Khadija Hanim
Neslishah Sultan (1921-2012)
Formerly in the Collection of Emperor Napoleon I and the House of Hohenzollern
Historically Important and Highly Significant Diamond Brooch/Pendant
Estimate: 120,000 – 200,000 CHF
SOLD: 3,527,000 CHF ($4.4 million USD)
The circular jewel featuring an oval diamond weighing 13.04 carats surrounded by Old Mine- and Mazarin-cut* diamonds, within an openwork border, further enhanced by more Mazarin-cut* diamonds. The item has been dated as circa early 19th century.
*Mazarin Cut – 34-faceted cushion-shaped diamond cut from the mid-1600s, featuring 17 crown facets and 17 pavilion facets
The brooch has been described as silver-topped 14 karat gold. The center diamond has been given a color grade range of I-J, and a clarity grade of SI. The ten largest Old Mine Cut diamonds surrounding the oval have a total weight of approximately 16.00 to 17.00 carats, ranging in color grade from F to J, and ranging in clarity from VS to SI.
The brooch comes with royal provenance:
Emperor Napoleon I (1769-1821)
King Friedrich Wilhelm III of Prussia (1770-1840), presented by Lieutenant von Pless
Hohenzollern Family Jewels
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Two Historically Significant Napoleonic Jewels from the Hohenzollern Treasury
The historical and important diamond brooch/pendant above and unmounted green beryl (seen below) were heirlooms of the Prussian Royal House of Hohenzollern for over two centuries, both having a connection to Emperor Napoleon I. The former can conclusively be identified as a hat ornament left behind by Napoleon in his carriage when retreating from the battlefield at Waterloo. The beryl would have been worn by Napoleon at his coronation in 1804 according to tradition. Both jewels possess an extraordinary historical significance through their provenance of the illustrious House of Hohenzollern.
*The Hat: According to the BBC, “Historians say the hat was part of his brand. Wearing it sideways made him recognisable in battle. He owned about 120 bicorne hats over the years.” One of these bicorne black beaver felt hats was sold recently at auction (2023) for $2.1 million.
We hope that the owner of the hat also purchased the above diamond brooch to complete the pairing. Why not?
Historical and Important Unmounted Green Beryl
Having belonged to Napoleon I: Up for sale, an unmounted cushion-shaped green beryl weighing 132.66 carats. There is no mention of a professional gemological laboratory report.
According to Sotheby’s, the gem is in very good condition, with chips and small nicks to the girdle. The beryl is medium light slightly bluish green, slightly included, with a “reflective internal fracture” that is particularly visible from the side.
Estimate: 32,000 – 48,000 CHF
Sold: 838,200 CHF (just over $1 million USD!)
Green Beryl v. Emerald
So, what’s the difference between a green beryl and an emerald — or an aquamarine, for that matter?
Shane McClure, global director of colored stone services at GIA’s world headquarters in Carlsbad, California, reminds us that “This is a much more complicated question than you might think. Believe it or not, there is no standard definition for green beryl. Just as there is no agreed upon dividing line for when aquamarine becomes green beryl or even emerald for that matter. Below is a quote defining emerald from The Jeweler’s Manual by Liddicoat and Copeland, 1964:
‘The medium light to medium dark tones of slightly bluish-green or slightly yellowish green beryl.
There is no standard dividing line between emerald and either aquamarine or the lighter green variety known as green beryl.’
“I gave a talk on this very subject in Idar-Oberstein this year in May,” says McClure. “We all basically agree that to be emerald it must be colored by chromium and/or vanadium, and be predominately green.”
And without a lab report, we do not know what trace elements color the 132.66-carat Napoleon beryl.
Based on photographic observations alone, four of the five Sotheby’s images of the 132-carat gem show color that could be interpreted as emerald, while one of the five images, where the gem is held in hand, shows quite a bit of blue (images seen here). Judging color based upon internet images is never recommended. McClure notes that the market has seen an influx of material in recent years that drifts “too blue to be emerald – in the range of blue-green.” Some call it green beryl, others call it aquamarine.
As for the Napoleon “green beryl,” determining whether it is emerald or green beryl is especially difficult, if not impossible, based solely on the photographs provided.
In the end, this may be one of those gems whose classification, with or without a laboratory report, will remain open to interpretation.
TIARAS
Some might say tiaras have slipped out of fashion, but spend five minutes at a royal sale and you’ll learn otherwise. As Kerry Gregory reminds us [in our Tiaras feature here], not all head adornments are created equal: tiaras, diadems, and crowns each come with their own rules, histories, and very specific wearers. These pieces aren’t just “pretty headwear.” They carry centuries of social meaning and tradition, right down to who is permitted to wear what.
The examples crossing the block this past week at Sotheby’s Royal and Noble Jewels Auction in Geneva are hardly the plastic dress-up versions beloved by the pre-teen set. These are high-jewelry creations encrusted with diamonds and natural pearls, shaped by goldsmiths and court jewelers in some of the finest workshops of their era. Each one is a study in craftsmanship, heritage, and status. Their elegance and symbolism still resonate with collectors, dealers, and historians alike.
So let’s have a look at some of the tiaras that sold at Sotheby’s Royal and Noble Jewels Auction
Splendid Diamond Tiara
Here we have a graduated series of flowerheads, each set with Old Mine Cuts and pear-shape diamonds. The tiara was assembled in the 19th century from 18th-19th century floral pins. The tiara comes apart, with a detachable bracelet, and a detachable brooch. The large central flowerhead was originally an 18th century dress ornament.
Estimate: 110,000 – 160,000 CHF
Sold: 120,650 CHF ($151,000)
Estimated total diamond weight is approximately 50 carats. Color ranges from K to L, with clarities ranging from SI1 to SI2.
Provenance notes that the tiara was the property of Baron Gisborough (1856-1938).
Fine Diamond Tiara
Designed as a garland of wild roses, each flowerhead centers a stamen set en tremblant* with an Old Mine Cut diamond, surrounded by rose-cut diamond pistils. Its pavé-set petals, leaves, and rose buds detach to form five brooches, all resting on a frame created circa 1840.
*en tremblant: a French term meaning “to tremble.” Portions of the jewel are mounted on tiny springs so that they move or vibrate when the piece is touched or worn.
Estimate: 100,000 – 170,000 CHF
Sold: 393,700 CHF
The three principal Old Mine Cut diamonds are estimated to weigh approximately 8.00, 5.50, and 5.00 carats, respectively, on average M+ colour and VS1–VS2 clarity, as graded in the mount, with minor chips to the girdle on the largest stone. Two additional Old Mine Cut diamonds are estimated at approximately 2.15 and 2.00 carats, on average K–M colour and VS2–SI1 clarity. The remaining diamonds total approximately 60.00 carats, on average I–K, with some L–M colour, and SI, with some I clarity, all as gauged and graded in the mount.
Provenance: Henrietta Scott, Duchess of Portland (1774 – 1844), and then by descent to the great-granddaughter Margaret Greenhalgh, Countess of Norbury.
Charming Diamond Tiara
Circa 1880, this tiara was designed as a graduated series of detachable flowerhead motifs on a scalloped base, set throughout with Old Mine Cut diamonds and accented by rose-cut diamonds.
Estimate: 25,000 – 45,000 CHF
Sold: 48,260 CHF ($60,000)
The three principal flowerheads can be converted with brooch-clip fittings.
The diamonds in total are estimated to weigh approximately 30.00 carats, with an average range of I to J colour (with some K–L examples) and clarity graded as SI, (with some I clarities).
Provenance: Baroness Barracco (1860-1941)
Diamond Tiara
Estimate: 20,000 – 30,000 CHF
Sold: 25,400 CHF ($32,000)
Our next tiara seen here has been designed as a floral and leaf motif spray tied by a ribbon, with wheat sheaves extending from the arrangement. The details are set with Old Mine Cut diamonds and accented by Rose Cut diamonds; circa 1860.
The tiara is detachable in fourteen places, and comes with the proper number of screws, and fittings to wear the individual elements.
The total weight of the diamonds is estimated to at approximately 22.00 carats. On average, the diamonds have been color graded as I to K color, with some L and M examples, and all graded SI–I clarity.
Attributed to Boucheron
Diamond Tiara/Bracelet Combination
This beautiful tiara is designed as a laurel wreath, set with Old Mine- and Old European-Cut diamonds, and accented by rose-cut diamonds. The diamonds are estimated to weigh a total of approximately 22.00 – 24.00 carats.
The center diamond is estimated to weigh approximately 1.50 – 1.60 carats, graded I-J in color, and SI in clarity.
Estimate: 20,000 – 30,000 CHF
Sold: 57,150 CHF ($71,000)
The tiara is detachable from the frame to be worn as a bracelet; Dated circa 1880, and accompanied by a case stamped Boucheron.
Provenance: From the Estate of the Countess of Faber-Castell
