The Inside Scoop on the Wedding Gown Blake Lively Flipped Out Over

By this point, Blake Lively has proven that she loves a gorgeous gown. “It’s fun to dress up in a big sparkly number,” she has told PEOPLE. And, the thing is, she doesn’t even have to be the one wearing the look to appreciate a design’s splendor.

Last weekend, Lively attended her friend Jessica Snyder’s wedding at the Tribeca Rooftop in New York City, where she posted two photos on Instagram of Snyder and her look, calling her “the most beautiful bride on the planet” and “the best friend I could ask for.”

The bride, who worked as Lively’s assistant for three years, from 2010 to 2013, wore an embellished design by Marchesa, which Lively pointed out had “killer details” on Instagram.

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https://www.instagram.com/p/BLFDL5VA0l9/?taken-by=blakelively

The pals share a love of the label, as Lively wears Marchesa’s gowns on the red carpet often, and even wore Marchesa to her wedding to Ryan Reynolds in 2012.

And after working for Lively, Snyder moved on to be the personal assistant to Marchesa designer Georgina Chapman until 2015. (Below, Snyder at a fitting with Chapman.)

So, what makes this wedding look so flip-worthy? It was custom designed, the team at Marchesa tells PEOPLE, and took roughly 500 hours to create in the New York atelier.

While Chapman and her co-designer Keren Craig did not attend Snyder’s wedding to beau Selwyn Cummings alongside Lively, they did share a dinner to congratulate Snyder before her big day.

“I couldn’t be more thrilled for Jessica,” Chapman tells PEOPLE. “She was my assistant for over a couple of years and has grown into a dear friend. She made the most beautiful bride and I was honored that she chose to wear a custom Marchesa gown for her special day.”