Meghan Markle's Best Friend Jessica Mulroney Was Her Honorary Maid of Honor — and 'Something Blue'

Meghan Markle‘s best friend, Jessica Mulroney, sat just a few feet away from the former Suits star at her Saturday wedding to Prince Harry — and both Mulroney’s seat and her outfit had a special significance for the ceremony.

Mulroney “was dressed in blue and wearing blue sapphire earrings, so it was almost that she acted as [Meghan’s] ’something blue,’ ” says Eva Hartling, vice president of Birks at the Birks Group (Meghan’s go-to jeweler), describing the Toronto-based stylist as Meghan’s “unofficial maid of honor.”

“The children were officially her bridesmaids, but she [Meghan] made sure that Jessica was sitting in that first seat closest to where Harry and Meghan were standing,” Hartling tells PEOPLE.

“It was clear that she kept a special place for her close friends — even though they weren’t standing at the altar with her, they were in close proximity and I thought that was a very nice touch,” Hartling says. “The seating arrangement at the ceremony spoke volumes.”

Mulroney’s friendship with Meghan, 36, traces back years, as they’ve bonded in part over their philanthropic work. Mulroney has also styled some of Meghan’s signature looks since her relationship with Harry became public.

Mulroney’s 4-year-old daughter, Ivy, was also one of Meghan’s little bridesmaids who walked behind her down the aisle of St. George’s Chapel.

For the wedding and daytime events on Saturday, Mulroney accessorized with Birks Rosée du Matin Blue Sapphire Drop Earrings with Diamonds and Birks Snowflake Starry Night Oval Earrings, according to Hartling.

Jessica Mulroney leaves Windsor Castle after Meghan Markle’s wedding to Prince Harry on Saturday

Chris Jackson/PA Wire

For night, she transitioned to Birks Muse Large Citrine and Diamond Drop Earrings and a Birks Petalé Gold and Diamond Pendant.

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At the nuptials, Mulroney wore a dress in royal blue, designed by Montreal’s Antoinette Di Carlo — complete with cap sleeves and matching fascinator.

“We designed it together – it was a collaborative effort. It’s a fit and flare design with a cap detail on the sleeve, it was very classy and regal, Di Carlo tells PEOPLE of Mulroney’s dress. “We started working on it about two months ago. She’s worn pieces of mine before, but this was our first collaboration.”

“She wanted a look that was classy and timeless. Jessica chose the royal blue color. Jessica’s style is quite simple and very classy,” she says, adding that a similar version of the dress is available online.

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Adds Hartling, “I think the color blue was a nod to being the ‘something blue’ for her best friend. She chose something very elegant, keeping in line with the usual scene at a royal wedding. Blue suits her really well, I think its one her personal favorites and of course she chose our sapphire earrings, which complimented it all perfectly.”

After marrying Harry, 33, Meghan tried on some blue of her own for her evening reception look (designed by Stella McCartney). She wore one of Princess Diana’s aquamarine rings on her right hand while the soles of her custom-made white satin Aquazurra shoes were dyed baby blue.

Di Carlo, the woman behind Mulroney’s wedding look, tells PEOPLE being a part of the wedding “feels incredible!”

“I feel like I am a part of history,” she says. “It’s a lovely feeling, and I feel very proud and very grateful to Jessica for picking me, a local designer from Montreal, the town where she grew up.”