It's true—Sienna Miller's French skincare secret is only £12 this Amazon Prime Day.

      Sienna Miller has long been celebrated for her effortless beauty and flawless skin that appears naturally radiant. Thus, it raised quite a few eyebrows when the actress recently revealed her reliance on A313, a thick, pharmacy-grade retinoid cream that is quietly cherished in beauty circles. This simple French formulation comes in a retro metal tube, and while it lacks glossy packaging or a trending brand campaign, it has gained a devoted following for good reason.

      In contrast to stronger prescription retinoids, A313 incorporates a mix of vitamin A derivatives that gently encourage the skin to achieve a more radiant and smoother appearance without causing disruption. Miller mentioned that she learned about it from a friend—Alexa Chung—and pointed out how effective it is despite its modest cost. It’s precisely the kind of product that might be overlooked until someone like Miller casually includes it in her skincare routine.

      At the moment, A313 is available on Amazon for just under £13 during this Amazon Prime Day, a small fraction of what one might pay for a more upscale retinol serum with comparable effects. The charm of A313 lies in its straightforwardness—it serves as a well-kept secret among beauty editors and off-duty models that has circulated quietly for years. It’s the type of product you might not display prominently on your shelf, but you always ensure you have enough on hand.

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      Shop A313 Retinol on Amazon Prime Day

      A313

      Vitamin A Lightweight Face Cream

      Amazon Prime Day is a sale event specifically for Amazon Prime members, featuring some of the best deals you'll find on Amazon throughout the year, with promotions on top brands and products. The offerings cover everything from leading beauty items to the latest fashion, along with savings on tech and home goods as well. There are beauty tools we've been eager to try, health and wellness products for a summer refresh, chic home appliances, and many other great items in between.

      When Is Amazon Prime Day 2025?

      Amazon Prime Day is a biannual event that occurs in July and October each year. The next sale is currently underway, having begun on Tuesday, July 8, 2025, and will conclude on Friday, July 11, 2025. This makes July 2025's Amazon Prime Day sale one of the longest in the brand's history.

      How to Access the Amazon Prime Day Sale

      Amazon Prime Day sales are accessible to all Amazon Prime members. You can sign up for an Amazon Prime membership here. It’s free for 30 days, allowing you to enjoy all the benefits of the Amazon Prime Day discounts without any cost (just remember to cancel before the 30 days expire to avoid being charged the monthly fee).