Since her debut as Prince William’s leading lady in 2004, the public has fawned over the physical perfection that is Kate Middleton. Now as duchess of Cambridge and wife of the second in line to the British throne, Middleton’s allure has only grown. While the royal mom’s coveted designer duds command the most attention, the latest craze is her recently revealed skin care routine.

According to reports, Middleton, 32, is a longtime fan of Karin Herzog’s Oxygen Face Sabo-Regular Face Cream, a Swiss-made moisturizer that claims to contain 2 percent of “highly concentrated” oxygen as one of its main ingredients. Retailing for $65 USD, the 1.7 ounce oil-free item promotes its ability to deeply penetrate skin, neutralizing both bacteria and toxins to clear surface acne. “The light cream helps to enhance nutrient absorption, optimize skin functions and limit the formation of excess sunburn, clogged pores and blemishes,” reads the product’s description.

So does it work? While Middleton’s skin appeared both flawless and radiant during her most recent outing to Bletchley Park in England Thursday, some beauty insiders seem unconvinced about the effectiveness of the duchess’s go-to skin product.

Despite Herzog’s cream publicity, which advertises its ability to work on all skin types, including acne-prone, one beauty writer claims the product caused her to break out even after discontinuing use.

“Within three weeks of using Kate's products, I saw results. I had broken out mildly and my eyebrows were bleached to a tawny blonde,” reads Maggie Lange’s New York magazine report. Lange concluded her review stating that she felt too much of an “average commoner” to stick with the duchess’s regimen. “The takeaway of using royal emollients: It’s all a bit too-too. It was insufferably boring to smell like nothing and oxygen.”

According to another beauty insider's 2012 review, the product didn’t cause any adverse effects, but no noticeable improvements either. “The packaging is old-fashioned and they were particularly nice to use. … As usual, I couldn’t see any difference in my skin,” Alice Hart-Davis of the UK’s Daily Mail reported.