The final season of The Crown chronicles Princess Diana's final summer. The third episode finds her leaving the crowds with her lover, Dodi Fayed, in Monaco.

The couple, played by Elizabeth Debicki and Khalid Abdalla in Peter Morgan's hit Netflix series, take refuge in a jewelry store. Surrounded by shiny products, Dodi looks around and asks casually. “Is there anything here that you like? Anything?” “This is very nice,” Diana replies, turning her gaze to an advertisement with the slogan “Dis-moi Oui!” (“Tell me yes”). The ad features a domed cocktail ring with an emerald-cut center diamond. It is flanked by four smaller triangular-shaped stones.
When he learns that the ring shown on the poster is in Paris, Dodi takes his mistress to the Ritz. There he organizes a romantic dinner. To the soundtrack of Julio Iglesias“ ”When You Tell Me That You Love Me", he asks the princess to marry him. But did that actually happen?;
“In no way was I told that it was an engagement ring.” Said Alberto Repossi, of the Italian jewellery house, in two interviews. One for the Washington Post and the other for the French newspaper Le Figaro, published in September 1997. That is one month after the tragic deaths of Diana and Dodi in a car accident on August 31, 1997.
According to Mr. Repossi's original allegation, Dodi and Diana entered his boutique at the Hôtel Hermitage in Monaco on August 10 that summer. But they had already decided to buy a ring from the Dis-moi Oui collection. The couple had seen the ad in the French magazine L'Officiel. The ad showed a black-and-white photo of a woman and an enlarged image of the ring, with the slogan “Say yes to me!” and the words: “A small yes for the most beautiful day of her life. It was worth the wait!”

The pair met with Mr Repossi for a second time when he suggested they work on a bespoke piece with a different setting. The conversation turned to the creation of a bespoke jewellery range, including a bracelet. So more appointments were made and the jeweller delivered two rings to Dodi. The ring he had ordered and another to use as a model for future pieces they would design together.
After the accident, one of the two rings was returned to Repossi. However, another remained unpaid, forcing the jeweler to make an insurance claim. But it catapulted the house's name into the tabloids.
“My employees were offered money to share secrets. We were even offered a lot of money for the boutique's video surveillance system,” Mr Repossi told Le Figaro. “To stop this hysteria, I destroyed the designs and models of the jewellery in the workshop. I also stopped the jewelry campaign “Dis-moi Oui!” as well as the production of this model.”.

The Dis-moi Oui campaign which translates as “Say yes to me”.
On screen in the film The Crown, Princess Diana politely declines the marriage proposal. So then Dodi jokes that the ring should be renamed “Dis-moi Non!”. - Or Say Me No!" - suggesting that the marriage was not, in fact, on paper.
And yet, in an article published by the BBC in 2007 around the fatal car crash inquiry, Mr Repossi was quoted as refuting the 1997 position. So he implied that an engagement was in the offing. “I received a call from Dodi saying he needed that ring for the end of August. Because, in early September, their engagement would be announced,” Mr Repossi said.
Richard Horwell QC, a representative of the Metropolitan Police, questioned Mr Repossi about statements he made in 1997. But the jeweller replied: “I understand that it is a problem for you that they chose an engagement ring, but it is not my concern.
The reality, of course, is that we will never know the truth about the “secret engagement”, if it did exist. Further that fans of The Crown, which is a drama and not a documentary, should not look for anything approaching a history lesson in the show.
Source: vogue.co.uk