25/10/2017 7:22 AM AEDT | Updated 14/02/2018 6:46 AM AEDT

The One Thing You've Probably Never Noticed About Kate Middleton

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You'll never see her wearing this ONE thing! 

The Duchess of Cambridge gets to wear pretty things all the time ― an engagement ring from the late Princess Diana, gorgeous designer dresses and, of course, the literal crown jewels.  

But there’s one thing you won’t see Kate Middleton wearing while she’s out and about attending royal engagements: bright nail polish on her fingernails. 

“The royal ladies always wear natural nail polish because very bright, especially red, is seen as rather vulgar,” Diana Mather, director and senior tutor at The English Manner, an international protocol, etiquette and hospitality consultancy firm in the U.K., told HuffPost. 

“In the old days prostitutes and courtesans wore red nail varnish (as it was called then) and ladies didn’t want to be associated with anything like that, so they wore understated colors,” Mather said. “Royal ladies always keep their nails beautifully manicured, but if by some unfortunate mishap a nail gets chipped when out in public, it is much less visible if it is a natural shade.” 

William Hanson, a British etiquette coach and expert, agreed and said that brightly colored nails are seen as “tarty” by the British. 

“Nothing about any outfit any member of royalty wears should distract from the duty at hand,” he said.

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German Chancellor Angela Merkel welcomes Prince William, Duke of Cambridge and Catherine, the Duchess of Cambridge in the German Chancellery in Berlin on July 19. 

Grant Harrold, an etiquette expert who now runs a Twitter, YouTube and website called “The Royal Butler,” echoed Hanson’s thoughts. 

“The family would certainly not wear any form of product or makeup that will draw the wrong attention,” he said.

“Her Majesty the Queen wears a neutral polish, showing that royals do indeed wear nail polish, but opt for subtle and neutral colors keeping with tradition and not the latest fashion item.” 

Mather said that Queen Elizabeth II is a fan of the “Ballet Slippers” polish from Essie, which you can purchase here for $9. Middleton reportedly wore a similar shade for her 2011 wedding to Prince William

Andrew Milligan - PA Images via Getty Images
You can barely see the hint of polish! 

Middleton went with a similar, understated manicure for her engagement announcement photos with Prince William: 

Samir Hussein via Getty Images
Prince William and Kate Middleton pose for photographs in the State Apartments of St James Palace after news of their engagement on Nov. 16, 2010 in London, England. 
Samir Hussein via Getty Images
No polish in sight!

Throughout her time in the public eye, the Duchess of Cambridge has also kept her nails unvarnished or worn a lighter shade of polish at events: 

Matt Cardy via Getty Images
Kate Middleton, then-girlfriend of Prince William, hugs a friend on the second day of the Gatcombe Park Festival on August 6, 2005 near Tetbury, England. 
Fiona Hanson - PA Images via Getty Images
Kate Middleton attends the book launch party of 'Time To Reflect' by photographer Alistair Morrison, on Nov. 28, 2007 in London, England. 
Stringer UK / Reuters
Prince William and his fiancée Kate Middleton arrive at The Thursford Collection in Norfolk, England on Dec. 18, 2010. 
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The Duchess of Cambridge, Catherine Middleton and Prince William, Duke of Cambridge leave the King Edward VII hospital on Dec. 6, 2012 in London, England. 

Now, this news doesn’t mean that Middleton hasn’t ever worn bright nail polish before (she hasn’t been a royal her entire life). And we’ve seen her wear red nail polish on her toes at a dinner at Claridge’s in 2012.  

The Duchess of Cambridge arrives for a dinner given by The Thirty Club at Claridge's in London. 

And more recently she wore a similar red nail polish color on her toes earlier this year to a reception at Clärchens Ballhaus in Berlin, Germany. 

Retropix/Splash News
Duke & Duchess Of Cambridge attend a reception at the the Clarchens Ballhaus, the last original dance hall in Berlin, Germany in July 25. 

Though it seems that royals wouldn’t necessarily wear bright nail polish on their toes, Mather offered an explained for Middleton’s choice. 

“The correct dress code states that toes should not be on display, but that rule is more relaxed in the 21st century, so perhaps the Duchess of Cambridge likes to be a bit more adventurous where her toes are concerned,” Mather said. 

Just don’t count on Kate wearing bright blue or a sparkly pink polish on her fingernails any time soon (unless Princess Charlotte is able to convince her!)