Prince Harry and Meghan Markle announced their engagement Monday after months of speculation, but it's not just the actress' engagement ring that has led some to do a double take. Many are taking note of Markle's style choices following her engagement, which has proved to be influential in driving sales for the designers she chooses. 

The world's fascination with the British royal family stems from England's historical impact on everyone and everything, which is said to have allowed them to become a "global brand." When Kate Middleton took on the role Dutchess after marrying Prince William, her influence over fashion boosted the country's economy with $1.5 billion in sales, according to a 2012 study. This proved Middleton's fashion choices are impactful over sales, and Markle appears to be following in her footsteps. 

The "Kate Effect" has been unmatched so far, with even A-list celebrities in America not having the ability to carry sales the way she has. Markle's fashion influence challenges Middleton's as many of her items continue to sell out. The actress' power could potentially prove to be stronger than Middleton's.

Markle, 36, first stepped out with Prince Harry at the Invictus Games in September wearing a pair of the "Percy tortoiseshell sunglasses from Finlay & Co. The sunglasses, which retail at $180, reportedly sparked a 1,000 percent increase in sales for the brand after Markle's unofficial endorsement. This resulted in about $26,000 in sales. 

"We've been amazed by the response to Meghan Markle wearing Finlay & Co. during her first public appearance with Prince Harry," said Finlay & Co's Managing Director David Lochhead, according to Yahoo UK. "Our Percy sunglasses have been a top seller all summer and we're honored that Meghan chose to wear them on a day when the world’s press attention is on her."

"We've been fortunate to have many recognizable faces wear our sunglasses including Gigi Hadid, Jenson Button, David Gandy, Cara Delevingne and Rihanna...none of them have had the immediate impact that Meghan has made. There is a different reaction from the public when someone so connected to the royal family wears our sunglasses," Lochhead added. 

Markle's $517 engagement dress proved to be a hot commodity for Italian label P.A.R.O.S.H. after it sold out in under an hour. The brand is now taking pre-orders for the dress in three different colors, which will ship out to customers on Dec. 13. 

"The dress was sold out in less than one hour in all shops and online." Now that's some serious fashion influence," Paolo Rossello, the founder of P.A.R.O.S.H., told the Telegraph. "The Meghan Markle Effect is real, but there's a silver lining: You can buy the now-famous engagement dress!"

Markle has worn multiple items that have seen this level of success for the designers. Her Invictus Games dress from Aritzia, leather tote bag from Everlane and white button-down shirt from friend Misha Nonoo had all sold out moments after the actress was spotted wearing them. Markle's shoes from Sarah Flint, however, haven't been restocked at this time.

The likelihood that this success could trickle down to the designer Markle chooses to create the dress for her spring wedding is strong, too. This is a probable scenario considering the impact Pippa Middleton, the Dutchess' sister, and her gown had on summer wedding gown trends.  

"Classic and simple is the name of the game, perhaps with a modern twist. I personally prefer wedding dresses that are whimsical or subtly romantic," Markle said of her ideal wedding dress in a 2016 interview with Glamour. "Delphine Manivet and Christos Costarellos are faves of mine for their uniqueness and beauty. And I will always be a fan of Ellie Saab. J. Mendel is spectacular as well, especially for more structural designs."