Kate Middleton has "perfected her execution" of the high standards of royal dress code, etiquette rules and image that have been set for her, according to a professional makeup artist.
Saffron Hughes, who works at FalseEyelashes.co.uk, praised the Princess on following the strict guidelines which dictate that royals should not wear heavy eye makeup, or use bright lipstick colour.
However, it seems that Kate made a recent slip up and broke one of the beauty rules during the Christmas holidays, the Express reports.
The Princess of Wales attended a special Christmas carol service at Westminster Abbey in December 2021 with her husband Prince William and their children.
Kate opted for a very festive look for the occasion with a red dress coat and red lip gloss, which is a very bold choice for the royal who usually always goes for nude lip colours.
Other royals have also been spotted breaking the beauty rules many times, including Princess Eugenie and Princess Beatrice.
Beatrice in particular loves experimenting with her style and trying out new looks so she often opts for bright red lippy, which perfectly compliments her auburn hair.
According to beauty experts at FalseEyelashes.co.uk, these are the five main beauty rules that Kate follows but other royals seem to rebel against:
Never wear bright lipstick
The Princess of Wales is rarely ever seen wearing bright lipstick so red lip gloss at Christmas was a huge change for her and something she isn't actually supposed to wear.
The beauty artists explained: "The hidden pitfalls associated with wearing bright lipstick means it's a huge no-no for royal protocol.
"Bright lipstick can easily lead to a wardrobe malfunction, such as transferring to clothes, your teeth or even just looking too harsh against the skin."
However, while Kate makes an effort to follow this rule, there was one very important royal who preferred not to do so - Her Majesty Queen Elizabeth.
The late monarch was often seen sporting her own signature bright pink lipstick and her daughter Princess Anne is often seen wearing a bold red lip colour which she even has on at some royal events.
Never overdo face makeup
The Princess of Wales is naturally beautiful and wears very little makeup on her skin.
The beauty experts described Kate's every day look at public events as "flowy skin, thick brows and rosy pink cheeks".
However, she has previously taken her makeup game a bit further with a subtle smokey eye at red carpet occasions.
Never wear heavy eye makeup
The Princes of Wales occasionally goes for a smokey eye at more glamorous events but for her day-to-day affairs, her eye makeup remains "bright and natural", the beauty experts explained.
Explaining why heavy eye makeup is a no-go, they said: "Heavy eye makeup has a habit of straying underneath the eyes throughout the day, meaning wearing it at royal meetings wouldn’t picture well.
"Instead, Kate opts for eyeliner on the outer corner of the lower lash line, a matte brown eyeshadow on the lid and a coat of mascara to brighten the eyes."
Never wear heavy contour
The royal rules state that there is a "a no tolerance policy for heavy makeup, contour included".
Kate instead goes for a "dewy foundation and liquid highlighter which accentuates cheekbones just as much as a contour shade would".
Makeup mustn't run
It is essential that the royals' makeup lasts until the very end of long days at official events which can sometimes last for countless hours.
Kate gets around this with the use of a good primer and strong setting spray.
The expert explained: "Kate will come to events with makeup at her arsenal in case of emergencies, however it's likely it’ll go unused.
"Another beauty rule is that the royal women mustn't touch up their appearance in public so instead, Kate will use a budge-proof setting spray and primer."
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