On February 6, Queen Elizabeth II will become the first British monarch to reach a Sapphire Jubilee, 65 years after she ascended the throne. It's an incredible milestone, but it's unlikely the Queen will be celebrating her achievement, reports Harpers Bazaar.

Multiple reports suggest the Queen will spend the day in private at Sandringham, where she will go through her red boxes of official documents as usual. According to royal sources, she will avoid any public engagements and will remain in "quiet reflection" as she remembers her father, King George VI.

"It's important to understand that for the Queen this marks the anniversary of the day her father died," Dickie Arbiter, the Queen's former press secretary, explained to The Telegraph.

"She has always made it clear that her long reign is a consequence of her father's early death and so it is not a day for celebration.

"She will go to church the day before and her father will be in her thoughts then. On the day itself, she will do her red boxes but she won't be going out and about anywhere."

It's not unusual for Her Majesty to downplay such an occasion, though. In 2015, she surpassed Queen Victoria as the nation's longest-reigning monarch and although she thanked well-wishers on a visit to Scotland, the Queen said her record was "not one to which I have ever aspired".

While there's not expected to be any public celebration, the Royal Mint will honor the Queen's Sapphire Jubilee with a collection of specially designed commemorative coins.

As a reminder of the monarch's dedication to her public duties, the £5 coins have been engraved with an excerpt from a famous speech she gave as a Princess on her 21st birthday in 1947.

"My whole life, whether it be long or short, shall be devoted to your service," it reads.