A royal expert says Prince Charles' nickname for his daughter-in-law Meghan Markle reveals his true feelings about her.
The Prince of Wales reportedly refers to Meghan as "Tungsten", which he means as a compliment, the expert has said.
In this context, tungsten is intended to describe someone who is toughened and resilient.
"Meghan Markle hasn't had an easy time of it since joining the royal family," royal expert Christine-Marie Liwag Dixon explained on The List.
"She has also said that she felt less than at home in the royal family.
"The royal family may not have approved of Meghan and Harry stepping down as senior royals despite them doing so to escape an environment that was clearly not good for their mental health.
"However, it seems that Prince Charles had a lot of respect for Meghan's resilient nature," she added.
"This was evident in the secret nickname he reportedly had for her: 'Tungsten'.
"As royal correspondent Russell Myers revealed, Charles nicknamed her after the metal as 'she is tough and unbending'. Tungsten is the strongest naturally occurring metal on the planet," the expert continued.
Nicknames are common among the royal family. Kate Middleton reportedly calls her husband Prince William "Baldy", while William sometimes calls his wife "the Duchess of Dolittle".