Rachel McAdams - "Southpaw" New York premiere - July 20, 2015
Credit: Kevin Mazur/WireImage

It goes without saying that dressing for a wedding is tricky when you're the bride, but guests are also faced with a laundry list of style rules. Some of them may sound familiar (anything that bears even a little resemblance to white is a definite no); others are less obvious (wearing the same color as the bridesmaids can make it look like you're third-wheeling the wedding party). Still, even if you dodge a major faux pas and manage to find something suitable, you still want to look slammin', whether you're going stag or arm-in-arm with your future partner.

Wedding Guest Dress - EMBED 1
Credit: Christopher Polk/NBC; Axelle/Bauer-Griffin/FilmMagic; Don Arnold/WireImage

From left: Sophia Bush, Zendaya, and Miranda Kerr in Self-Portrait.

I was recently tasked with finding an outfit for a friend's wedding at the Ace Hotel in Shoreditch, an impossibly hip neighborhood in the East End of London. There was no dress code specified on the invitation, so I had little information other than the geographic location to steer me in the right sartorial direction. With the event looming at the back of my mind, I came across a photo of Rachel McAdams (pictured above) wearing a stunning off-the-shoulder midi-length dress with a cut-out at the bodice. It was perfect, not to mention culturally appropriate. It was by London-based label Self-Portrait.

Wedding Guest Dress - EMBED 2
Credit: courtesy Claire Stern

Me, with my date.

I wore it, and lo and behold, at that wedding and every subsequent one I've attended so far this summer, at least three guests have donned the brand's trademark laser-cut designs. It was as if some higher fashion power declared out of nowhere that Self-Portrait was the preeminent wedding guest dress designer. But it's easy to understand why: Launched by Han Chong in late 2013, the label is decidedly feminine with a cool twist—modern without being overtly sweet. Thus, ideal for a wedding. "Our dresses make women feel special, which is how people want to feel when they are attending a memorable occasion like a loved one's wedding," Chong recently told me.

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Another reason? The prices are shockingly reasonable. Self-Portrait's pieces range from $500 to $700 (sometimes even less on The Outnet). One girl at the London wedding had scooped up hers—a hot pink maxi—off the sale rack at Selfridges for less than $100. "I knew from the start that I wanted to democratize luxury goods and make beautifully crafted pieces without the price tag that usually comes with it," Chong added. "The right statement dress on the right woman creates a very special moment. When she looks at that piece in the future, she will always remember where and when she wore it."