Princess Mary and Prince Frederik look loved up in Paris on day one of royal tour

Princess Mary has proven – once again – she knows how to perfectly put together an outfit, showcasing two incredible looks in the fashion capital of the world, Paris.

The Danish royal is in France for a three-day working visit with her husband, Crown Prince Frederik.

Frederik and Mary are leading a business delegation of around 50 Danish companies and business organisations, participating in a business promotion under the heading 'Denmark and France - together for a better life and a sustainable future'.

Day one saw the royal couple pose for photographs at La Grande Arche, known as the new Arc de Triomphe, in the La Défense business district.

Frederik officially opened the event, which aims to strengthen relations between Denmark and France and to support the growth and position of Danish companies in the French market.

Mary wore a new outfit, custom made for her by Danish designers Ole Yde and Birgit Hallstein. The blue coat dress featured a white pleated slip underneath, which the Crown Princess matched with white South Sea pearl earrings and bracelet by Danish designer Dulong.

The 47-year-old also showed off her new diamond ring which has been spotted several times on her right hand, in place of her engagement ring and wedding band.

Mary and Frederik attended the first of the day's events together before separating for the afternoon. Mary was given a tour of the Georges-Pompidou Hospital, one of Paris' 39 public hospitals.

Later, the Crown Prince couple reunited for a reception celebrating 30 years of La Grande Arche. Mary changed into a black polka-dot dress, by Black Halo, featuring a boat neckline for the occasion. She accessorised with a pair of diamond 'Kharisma Supernova' earrings by Dulong.

Prince Frederik and Princess Mary were due to conclude their first day in Paris with a dinner hosted by French President Emmanuel Macron and his wife, Brigitte.

Mary has a warm relationship with France's First Lady, having recently caught up with her during a solo visit to the capital in June.

It's been a busy time for the Australian-born royal, who recently promoted to Acting Monarch by her mother-in-law, Queen Margrethe.

The Crown Princess says she is "very proud" to take on the duties of the Queen should the 79-year-old ruler be ill, travelling overseas, or unable to fulfill her constitutional role as monarch.