Blake Lively [1] looked extra glamorous [2] on the red carpet at the Cannes Film Festival [3] in early May — and now we know why. As a face of L'Oréal Paris and a star of the festival's opening-night film, Café Society, Blake has had gorgeous dresses [4] and Charlotte Tilbury's makeup skills to look utterly gorgeous.

Charlotte, however, spilled the beans on one of Blake's best beauty secrets when she posted a behind-the-scenes snap of their time together. "Thank you Blake," Charlotte wrote, "for introducing me to the best kept secret: @themakeuplight. It's changed my life!"

So what, exactly, is this gadget that surprised even a beauty guru on the level of Charlotte Tilbury? The Makeup Light [5], which is available online, is a portable LED light stand that purportedly mimics daytime sun inside. Because it's easy to pack up and take on the road, it's understandable why someone like Blake — who jets from event to event regularly — would fall in love with such a gadget. With the Makeup Light, Charlotte and Blake can see how a full face of makeup looks in the hot sun and before a sea of flashbulbs.

But, of course, such a tool doesn't come cheap. The Makeup Light's starter package is priced at $360 — and go up to $1,299.

The Makeup Light

The luxe version of the Makeup Light, the Studio Kit [6], sells for $1,299.

The Makeup Light's introductory package, the Key Light Kit [7], sells for $360.

The Results

Charlotte did Blake's makeup using L'Oréal Paris products. Blake finished the look with a yellow Valentino gown [8] for a lunch during day two of the 2016 Cannes Film Festival.