The Inchiquin Emerald: Between Clontarf and St James’s

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A jewel named for a dynasty is rarely as old as the dynasty itself, and the Inchiquin Emerald — currently on display at Hancocks London — is a particularly clean illustration of that gap.

The stone comes from Colombia. The setting was made in England around 1890. The name, however, reaches back through the Tudor period to the eleventh-century battlefield of Clontarf and the death of Brian Boru, the only Gaelic Irish king widely held to have ruled the whole island. Three geographies, three epochs, one object: a layered structure worth taking apart one strand at a time.

The headlines are these. A 5.67ct antique Colombian emerald, set with old mine and old European cut diamonds totalling approximately 10.50 carats, in a convertible bangle-and-pendant mount of late-Victorian craftsmanship, offered by Hancocks London, with provenance to the O’Brien family — Barons of Inchiquin, direct male-line descendants of Brian Boru, and one of the few Gaelic Irish lineages whose continuity into the modern peerage is documented to the generation.

The Swiss Gemmological Institute (SSEF) has issued not only its standard report but also the Appendix letter, which the laboratory reserves for stones it considers exceptional. The price is on application. Each of those strands — the gem, the mount, the dynasty — rewards a closer look.

The Stone, Untreated

SSEF describes the emerald as an octagonal Colombian gem of remarkable size and weight, with an attractive green colour, fine clarity, and — crucially — no indications of clarity modification in fissures at the time of testing. That last detail carries more weight than its phrasing suggests.

SSEF’s filler quantification scale runs from “no indications of clarity modification” through minor, moderate, and significant amounts of oil, resin or wax. The vast majority of commercial emeralds receive at least minor treatment, since the brittle stone forms with characteristic fissures that respond readily to filling.

An untreated Colombian of 5.67 carats with the colour and clarity the SSEF Appendix letter requires is a rare object in absolute terms — the kind of stone that, at the major auction houses, regularly anchors seven-figure single-lot results. The Appendix letter itself is awarded only to gems SSEF considers exceptional; the laboratory issues it free of charge, attached to the report, and it is among the closest things in coloured-stone gemmology to a formal mark of distinction.

The stone’s geographical journey is not documented from mine to setting, but it follows a familiar nineteenth-century pattern. The mines of Muzo and Chivor, in the Cordillera Oriental of the Colombian Andes — the emerald-bearing region also associated with the Coscuez deposits — had reopened to direct European trade after independence from Spain in 1819, and by the second half of the century, Colombian material was reaching London and Paris in significant volume, often via Bogotá and the Antwerp cutting trade. The colour profile SSEF describes — vivid green hues pronounced by well-proportioned cutting — is consistent with Muzo material of the period, though the laboratory does not, as a matter of policy, distinguish between Muzo, Chivor and Coscuez on its origin reports.

A Late-Victorian Cluster

The setting was made some years later, and probably in London. Hancocks dates it to circa 1890, and the construction supports the reading: the octagonal emerald held in yellow-gold claws, framed by twelve old mine cut diamonds, then by a radiating star of eight old European cut diamonds with diamond points accenting the angles — a clustered composition typical of the high Victorian period.

The convertibility between bangle and pendant was an admired feat of late-nineteenth-century jewellery engineering rather than an afterthought: bangles were the dominant evening jewel of the 1880s and 1890s, and the ability to detach the central cluster as a pendant gave the wearer both daywear and full-court versatility from a single commission. No maker’s mark or workshop attribution has been published, but the quality of the craftsmanship and the social context of the commission — a wedding gift within the Anglo-Irish aristocracy — point firmly to one of the established London houses of the period.

Lady Ethel and the Foster Gift

The jewel was given to Ethel Jane Foster on her marriage, on 14 January 1896 at Richard’s Castle, near Ludlow in Shropshire, to the Honourable Lucius William O’Brien, eldest son of Edward Donough O’Brien, 14th Baron Inchiquin. The gift came from Ethel’s mother — a detail documented in Lady Ethel’s own will of 1939, which describes “my large emerald and diamond bracelet given me by my mother on my marriage.”

This means the emerald entered the O’Brien family only at the 1896 wedding; its earlier life, in the hands of the Foster family, remains untraced. Ethel’s father, Johnston Jonas Foster, was a Justice of the Peace from Cliffe Hill, Lightcliffe in Yorkshire — a family of evident means, but one whose connection to the jewellery trade or to the London dealers of the 1880s and 1890s has not been documented. How the Fosters came to possess a Colombian emerald of this calibre is an open question, and one that adds a further layer to the provenance story.

Four years after the wedding, in 1900, Lucius O’Brien succeeded his father as the 15th Baron Inchiquin (1864–1929), serving as Irish Representative Peer in the House of Lords and holding, by inherited Gaelic tradition, the titles of Chief of the Name of O’Brien and Prince of Thomond. Lady Ethel (1867–1940) wore the jewel for over four decades; she died in 1940, and the bangle passed by descent through the couple’s children.

It is in this half-century of biography that the jewel acquires its most tangible history — wear, inheritance, the slow patina of a particular hand and a particular court calendar.

A Lineage to Brian Boru

The O’Brien connection reaches far deeper than any single jewel. The family’s claim to descent from Brian Boru — Ard Rí Érenn from 1002 until his death at Clontarf on 23 April 1014, and, in the framing of Trinity College Dublin’s archival catalogue, “the first king who could truly claim to rule the entire island of Ireland” — is genuine, documented, and unusually well-attested by the standards of medieval Gaelic genealogy.

The 18th Baron, Conor Myles John O’Brien (1943–2023), was confirmed by Y-DNA testing as the 32nd-generation male-line descendant. The current peer, the 19th Baron Conor John Anthony O’Brien (b. 1952), continues the unbroken line. Few European families can document this kind of continuity. Fewer still attach a named jewel to it.

A Title Made at Greenwich, 1543

The title’s institutional history adds its own precision to the narrative. The Barony of Inchiquin was created by letters patent on 1 July 1543 for Murrough O’Brien — the last Gaelic King of Thomond, who that year travelled to Greenwich Palace to surrender his royalty to Henry VIII under the Crown of Ireland Act 1542. He was created Earl of Thomond for his lifetime, with a special remainder of that earldom to his nephew Donough, and Baron Inchiquin in the male line of his own heirs. The Thomond earldom became extinct in 1855; the Inchiquin barony, with its accompanying Gaelic titles, has descended uninterrupted since 1543. Nearly five centuries of continuous holding within a single family is itself remarkable, and represents the most precise historical anchor for the jewel’s name — more so than the Clontarf battlefield, which predates the title by over five hundred years.

A Previous Market Appearance

The Inchiquin Emerald has appeared at auction in recent years. It was offered at Woolley and Wallis on 21 April 2023 as lot 1637, catalogued as a Victorian emerald and diamond bangle with O’Brien provenance and accompanied by SSEF report number 125424, dated 21 November 2022.

Estimated at £60,000–80,000, the bangle realised a hammer price of £500,000 — a result that speaks to sustained collector appetite for heritage-provenance coloured gems at this level. The same sale included an important diamond parure, lot 1636, also from the Inchiquin collection.

The jewel’s presence at Hancocks London, now offered under the name “the Inchiquin Emerald” at the firm’s Georgian townhouse on St James’s Street, marks the latest chapter of its journey.

The Inchiquin Emerald belongs to an exceptionally small group of named heritage jewels available today. Its importance has several levels: the strength of its provenance, its rarity, and the remarkable gemmological qualities and beauty of the emerald itself. Jewels of this calibre come to market very rarely, and to find a Colombian emerald of such quality with provenance connected to Irish nobility and set in such a beautifully crafted antique jewel is unheard of. We are incredibly excited to be able to offer collectors an opportunity of this significance.

Guy Burton, Managing Director, Hancocks London

Three Strands, One Jewel

What the Inchiquin Emerald offers is not a thousand-year artefact but something richer in its complexity: a museum-quality untreated Colombian emerald, in an intact and beautifully engineered late-Victorian convertible mount, carrying the name of one of the oldest continuously-held titles in the Peerage of Ireland — now presented by a house that has held Royal Warrants since 1849 and has manufactured the Victoria Cross since 1856.

Each strand — the stone’s rarity, the setting’s ingenuity, the dynasty’s reach, the unanswered question of the Foster gift — makes the jewel more legible, not less. And it is that legibility, ultimately, that separates a named jewel from a merely expensive one.