One side of the gold coin features the Thai flag and the flag of the nation that the royal guest represents.

The other side of  the coin illustrates the royal projects of His Majesty.

Hand in hand, Their Majesties the King and Queen welcomed the royal guests from 25 nations to the Chakri Throne Hall and its new extension, the Borommaratcha-sathit Maholan Throne Hall, where they enjoyed a glamorous state dinner to mark His Majesty's 60 years as King.

The Chakri Throne Hall, in the Grand Palace compound, was illuminated with glittering lights, showing off its marvellous structure. The palace, built during the reign of King Chulalongkorn, is a combination of European-style architecture with a Thai castle-like top. It is inside this palace that King Chulalongkorn signed an end to slavery in Siam more than 100 years ago.

It was a night of formality and splendour, that started with the arrival of Their Majesties the King and Queen and the other members of the Royal Family at about 7.45pm, as they got ready to welcome the kings, queens and royal representatives from 25 countries for the state dinner.

The royal banquet capped the grand celebrations of the King's 60th anniversary on the throne.

On Monday, the royal guests attended a reception party at the Ananta Samakhom Throne Hall before going to watch the historic Royal Barge Procession down the Chao Phya River. They also enjoyed an exhibition of the King's royal projects at the Royal Navy Convention Centre.

Last night, the King wore a royal uniform, while the Queen was dressed in glittering black with a shiny crown on her head. They stood inside the main hall of the Chakri Throne Hall to greet the royal guests one by one. At the entrance of the throne hall, HRH Crown Prince Vajiralongkorn and HRH Princess Maha Chakri Sirindhorn stood by to welcome the royal guests before they were led in to greet Their Majesties.

After the greetings, the royal guests proceeded to an inner chamber awaiting all to arrive before they headed in for the state dinner.

Like the royal reception on Monday, the first royal guest to arrive was Sayyid Shihab bin Tariq Taimou Al Said, adviser to the Sultan of Oman. And the last to arrive were Sultan Haji Hassanal Bolkiah Muizzaddin Waddaulah and Raja Isteri Pengiran Anak Hajah Saleha of Brunei.

The overall dress of the kings, queens and royal representatives looked even more formal and glamorous than that worn for Monday's royal reception.

Crown Prince Philippe of Belgium wore a dark uniform, while Princess Mathilde looked elegant in a beautiful white gown and her ever-present smile.

Crown Prince Haakon and Princess Matte-Merit of Norway were also a handsome couple. The prince wore a dark uniform suit, while the princess wore a red dress.

The Prince of Orange, Willem-Alexander, also appeared in full uniform, while Princess Maxima of the Netherlands wore a long white dress with pink flowers.

Again, Jigme Khesar Namgyel Wangchuck of Bhutan was dressed in his traditional robe.

Princess Lalla Salma of Morocco looked as beautiful as ever with her long curled hair and a stunning red dress.

Queen Sofia of Spain, who wore a diamond crown, did not kiss His Majesty the King - as she did on Monday during the reception party. But she did give a slight kiss to the cheek of Queen Sirikit.

Emperor Akihito of Japan wore a long-tailed suit with decorations while Empress Michiko was dressed in white skirt and dark blouse.

King Carl Gustaf and Queen Silvia of Sweden looked very comfortable - they have been frequent travellers to Thailand, formally and informally. The king wore a white royal uniform, while the queen wore a light purple gown with a broad collar.

Their Majesties led the royal guests to attend the state dinner in the Borommaratchasathit Maholan Throne Hall, which was completed for these celebrations. The building looked splendid with a Thai-style roof, three storeys above the ground and two storeys of basements. The state dinner was held on the second floor. The third floor is reserved for welcoming royal guests on important state visits. The first floor is the entrance and connected with the Chakri Throne Hall.

During the state dinner, the King expressed his thanks to the royal guests for taking part in the jubilee celebration. Sultan Haji Hassanal Bolkiah Muizzaddin Waddaulah, the most senior monarch in terms of years on the throne, spoke on behalf of other royal guests to give a blessing to the King. The Sultan has ruled Brunei for 49 years.

As part of the jubilee celebration, the King gave each of the royal guests a gold coin at the end of the state dinner as a souvenir. One side of the gold coin features the Thai flag and the flag of the nation that the royal guest represents. The other side of the coin illustrates His Majesty's royal projects.