The British Royal Family Attend The Queen's Diplomatic Reception at Buckingham Palace on December 04, 2018 in London, England.

Catherine, Duchess of Cambridge dazzled in a Cambridge Lover's Knot Tiara that once belonged to Princess Diana as she arrived for a glittering Buckingham Palace reception on Tuesday night, pictured

Catherine, Duchess of Cambridge joined husband Prince William, Duke of Cambridge and hundreds of esteemed guests for the Queen's the Diplomatic Reception 2018, an annual white tie affair and one of the highlights of the royal calendar

A glimpse of Catherine, Duchess of Cambridge's outfit could be seen through the car window as she arrived at the Diplomatic Reception, The Duchess appeared to be wearing a sparkling white gown with metallic silver detailing on the shoulders

Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge arrived at Buckingham Palace together in the back of a chauffeur-driven Bentley

The Duchess of Cambridge put on a dazzling display in the Lover's Knot tiara as she arrived at the venue, dressed in a sparkling white gown with metallic silver detailing on the shoulders wearing the Royal Family Order of Queen Elizabeth II

Catherine, Duchess of Cambridge teamed the tiara with a pair of pearl drop earrings, putting on a sparkling display in the dress

Queen Elizabeth II was also spotted as she greeted guests at an evening reception for members of the Diplomatic Corps at Buckingham Palace in London, putting on an even more dazzling display in The Girls of Great Britain and Ireland Tiara with matching necklace and earrings

The Duchess of Cambridge wearing a Lover's Knot tiara, she accessorized with a favorite pair of pearl drop earrings and proudly wore the yellow ribbon of the Queen's Royal Order pinned to her chest

Queen Elizabeth II was followed by Prince Charles, Prince of Wales, Camilla, Duchess of Cornwall, Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge, just seen, as she made her way into the lavish affair

Prince Charles of Wales and wife Camilla, Duchess of Cornwall greeted guests together as they supported the Queen at the annual palace reception on December 4, 2018

Camilla, Duchess of Cornwall was resplendent in an oyster colored satin evening coat, which she wore over a floor-length gown opted for The Boucheron Tiara, as she arrived with Queen Elizabeth II (front center) and Prince Charles, behind them is The Duke and Duchess of Cambridge

Queen Elizabeth II, 92, looked regal in a white gown with delicate tiered lace overlay as she greeted the ambassador of Norway at the evening reception at Buckingham Palace. The monarch paired the dress with a metallic gold handbag and heels

The Duchess of Cambridge appeared animated as she spoke to guests at the Diplomatic Reception on December 4, 2018

Catherine, Duchess of Cambridge embellished dress glimmered beneath the soft lights of the Buckingham Palace room where guests mingled.

Queen Elizabeth II looked animated as she spoke to the ambassador of Kuwait - one of the roughly 1,000 guests invited to the reception

Queen Elizabeth II greeted the ambassador of Honduras as Prince Charles and Camilla, Duchess of Cornwall followed her down the line of guests

Radiant Catherine, Duchess of Cambridge appeared perfectly charming as she spoke to guests ahead of the lavish meal at the Diplomatic Reception at Buckingham Palace on December 4, 2018

Queen Elizabeth II beamed as she was introduced to the esteemed guests invited to share in the festivities at Buckingham Palace

Queen Elizabeth II put on a regal display in floor-length satin gown with a delicate tiered lace overlay, top it off wit The Girls of Great Britain and Ireland Tiara, she accessorized with a metallic gold handbag and shoes as she makes her entrance to the Diplomatic Reception at Buckingham Palace

The Duchess of Cambridge has been pictured wearing the Royal Family Order of Queen Elizabeth II, pictured, for the first time

Catherine, Duchess of Cambridge wore Alexander McQueen gray blue taffeta gown, paired with a diamond and pearl Cambridge Lover's Knot tiara to the state dinner at Buckingham Palace in October 2018

The Duchess of Cambridge most recently wore the Lover's Knot Tiara to the state banquet held in honor of Queen Maxima and King Willem-Alexander of the Netherlands in October 2018

Catherine, Duchess of Cambridge walked alongside Rear Admiral Ludger Brummelaar as she made her way into the State Banquet 2018 at Buckingham Palace. The Duchess of Cambridge donned a flattering blue dress by Alexander McQueen for the occasion.

Catherine, Duchess of Cambridge wore the Cambridge Lover's Knot Tiara for the annual Diplomatic Reception at Buckingham Palace in December 2016, pictured

The Duchess of Cambridge in the Cambridge Lover's Knot Tiara at the annual gala in 2015

Catherine, Duchess of Cambridge opted for the diamond and pearl Cambridge Lover's Knot tiara owned by Princess Diana for a lavish State Banquet held in honor of the visiting Dutch Royals in October 2018, pictured.

Catherine, Duchess of Cambridge in an ice blue Alexander McQueen gown, opted for the diamond and pearl Cambridge Lover's Knot tiara to the State Dinner at Buckingham Palace in October 2018. The glittering piece was crafted by royal jewellers in 1914. The Duchess also wore the Elizabeth II Family Order - a jewel encased image of the Queen on a chartreuse yellow ribbon

Catherine, Duchess of Cambridge appeared in excellent spirits, beaming as she mingled with the guests at the lavish Diplomatic Reception at Buckingham Palace

Catherine, Duchess of Cambridge greets guests at an evening reception for members of the Diplomatic Corps at Buckingham Palace on December 04, 2018 in London, England.

Catherine, Duchess of Cambridge glittered in an off-white Jenny Packham gown that is embellished with silver crystals and designed with a slight cowl neck and cap sleeves accessorised with a favorite pair of pearl drop earrings and finished with the stunning Cambridge Lover's Knot Tiara for the Buckingham Palace lavish reception

Catherine, Duchess of Cambridge stunned in an off-white Jenny Packham embellished dress. She dazzled in the Cambridge Lover’s Knot Tiara that once belonged to Princess Diana as she arrived for a glittering Buckingham Palace for The Queen's Diplomatic Reception 2018.

Catherine, Duchess of Cambridge looked stunning in an embellished off-white Jenny Packham gown with a flattering cowl neck and capped sleeves, dons glittering headpiece, greets guests at an evening reception for members of the Diplomatic Corps at Buckingham Palace on December 04, 2018 in London, England.