Kate Middleton’s tiara moment at the Sultan of Oman state banquet was one of the most closely watched royal fashion moments of 2026 — a butter-yellow gown, the Queen Mary’s Lover’s Knot Tiara, and a set of honours and heirloom jewels that told a story of their own. Here is every detail explained, from the evening gown to the daytime outfit worn earlier the same day.

The state banquet was held at Windsor Castle on the evening of Tuesday 20 October 2026, hosted by King Charles III and Queen Camilla for Sultan Haitham bin Tarik of Oman. The Prince and Princess of Wales joined in hosting the Sultan, and about 160 guests sat down in St George’s Hall. Earlier the same day, Catherine had worn a forest-green coatdress for the official welcome — a colour that nodded to the flag colours of Oman.

The evening: a yellow gown, a cape, and a keyhole

Catherine wore a butter-yellow creped gown by Elie Saab with a keyhole cutout, as reported by USA Today. InStyle described the gown as sunshine-yellow, with a built-in cape and braiding at the neckline and a pleated silhouette. People noted that tiaras are worn only a few times a year — which is part of why this appearance drew so much attention.

One small mishap was widely reported: the gown caught under a chair leg during the King’s speech, according to People and Hello!. That detail does not appear in any official account of the evening, but it was widely reported in coverage of the banquet.

Kate Middleton’s tiara: the Lover’s Knot, explained

The tiara was the Queen Mary’s Lover’s Knot Tiara. It was made by Garrard & Co. and was reportedly commissioned by Queen Mary in the early 1900s, according to USA Today. Its design features diamond bow motifs with dangling oval pearls.

The tiara passed to Queen Elizabeth II and was frequently worn by Diana, Princess of Wales. Catherine has worn it multiple times since 2015, when she debuted it, and People notes she has worn five different royal headpieces. Her first tiara moment came on her wedding day in April 2011 — a different piece.

InStyle gave an estimated value for the tiara. That estimate is not presented here as a fact: there is no market price for a piece of this kind, and no official valuation has been published.

The honours: sash, star, family order and heirloom jewellery

With the gown and tiara, Catherine wore the Royal Family Order of King Charles, and the sash and star of the Royal Victorian Order, as reported by People. Hello! described the honours as the King Charles II Royal Family Order and the GCVO sash and star.

Her jewellery included the Greville diamond chandelier earrings and a diamond choker bracelet, also associated with Queen Mary, as reported by PureWow and Hello!.

The daytime outfit: green for Oman

For the official welcome at Windsor Castle earlier on 20 October, Catherine wore a long green Alexander McQueen coat and a hat with a bow, as reported by USA Today. InStyle reported that she rewore a Sarah Burton for Alexander McQueen coatdress previously worn in 2022 and 2025, with a Juliette Botterill fascinator, a quilted Chanel purse and Cassandra Goad earrings.

Green is a colour of the flag of Oman, and the choice was widely read as diplomatic dressing — a deliberate colour nod to the visiting head of state.

She also wore the Queen Alexandra Three Feathers Brooch, a piece associated with Diana, Princess of Wales. The brooch was given to Diana on her marriage in 1981, according to USA Today. It is diamond- and emerald-encrusted, dates to 1863, and was gifted to Princess Alexandra of Denmark on her marriage to King Edward VII, according to InStyle. It was given to Diana, and given to Catherine after she became Princess of Wales in 2022. It depicts the ostrich feathers of the Prince of Wales’s heraldic badge, and it can be worn with or without a drop emerald.

The portrait: two twists

Kensington Palace shared a portrait of the Prince and Princess of Wales by Greg Williams, taken at Frogmore House, on a staircase, with the caption “Ready for tonight’s State Banquet in Windsor”, as reported by Hello!.

Frogmore House is in Windsor Home Park, about half a mile south of Windsor Castle. It was the venue for the Duke and Duchess of Sussex’s private evening wedding reception in May 2018, hosted by the then Prince Charles, with William and Catherine among the 200 guests, according to Hello!.

InStyle reported two twists in the portrait. First, it was the first black-and-white state-banquet portrait for the couple. Second, Williams was a new photographer for such a portrait, known for intimate Hollywood portraits. The portrait shows the same yellow gown and tiara, the late Queen’s earrings and bracelet, the Royal Family Order and the GCVO sash and star; William is in white tie with miniature medals and orders.

In his banquet speech, King Charles said, as reported by USA Today: “Oman is one of Britain’s oldest allies and, after all these years, I pray, one of your closest friends.” He praised the Sultan’s work on diversification and decarbonisation, and Oman as a trusted interlocutor. Catherine sat beside the Sultan at the banquet.

Why this banquet mattered

The banquet was the ceremonial centrepiece of the first state visit by a Sultan of Oman in 44 years. Shipping through the Strait of Hormuz was under severe pressure at the time, and the political business of the visit followed the next day at Downing Street, with a joint statement on defence, trade and regional stability. Catherine’s central role in the diplomacy of the visit was noted by Hello! and by InStyle, citing royal biographers.

For what was actually agreed at the visit, see Sultan of Oman’s UK State Visit: What the UK–Oman Joint Statement Actually Agreed. For related royal coverage, see The Crown Comes to the Capital: King Charles III’s Historic State Visit to Washington and the USA HeadlineX homepage.

For US readers, the banquet was a reminder of how much of modern diplomacy is still done in person, in full ceremonial dress — and how closely every detail, from a tiara to a brooch, is read for meaning.

Frequently asked questions

What did Kate wear to the Oman state banquet?
A butter-yellow Elie Saab gown with a keyhole cutout and a built-in cape, worn with the Queen Mary’s Lover’s Knot Tiara, the Royal Family Order, the Royal Victorian Order sash and star, and Greville diamond jewellery.

Which tiara did she wear, and why is it famous?
The Queen Mary’s Lover’s Knot Tiara, made by Garrard & Co. and reportedly commissioned by Queen Mary in the early 1900s. It passed to Queen Elizabeth II, was frequently worn by Diana, Princess of Wales, and has been worn by Catherine multiple times since 2015.

What did she wear for the daytime welcome?
A long green Alexander McQueen coatdress — a rewear of a Sarah Burton design previously worn in 2022 and 2025 — with a Juliette Botterill fascinator, a quilted Chanel purse, Cassandra Goad earrings and the Queen Alexandra Three Feathers Brooch. Green is a colour of Oman’s flag.

Who took the portrait, and what was different about it?
Greg Williams, at Frogmore House. It was, according to InStyle, the first black-and-white state-banquet portrait for the couple, and Williams was a new photographer for such a portrait.

Updated: 27 October 2026. Sources: USA Today — Princess Kate dazzles in Princess Diana’s iconic tiara; People — Kate Middleton’s rare tiara moment in a yellow gown; InStyle — Kate Middleton’s sunshine yellow gown; Hello! — William and Kate’s Frogmore House portrait; InStyle — Behind-the-scenes portrait twists. No licensed photo of the 2026 Oman state banquet has been verified; the featured image for this article, when added, will be an older file photo and will be captioned as such.