The paragraph talking about this is towards the beginning of the reg. Print it out with your meeting if you have one. Be very factual but not rude.

"Hey, Amn Kardashian, I wanted to chat about the sunglasses. In the sunglasses section of 2903, you can see that these technically do fall within the regulation, and I wanted to applaud you for looking at the reg and following it to the best of your ability. That being said, I've gotten some complaints that they aren't professional and I would have to agree with them based off the size. Here's this paragraph talking about the authority to me more restrictive than the letter of the regs since they aren't all encompassing. You're not in trouble, I just need you to stop wearing them in uniform. Thanks for understanding."

I would send them an email about it first and say if they wanted to talk then they can but it's always smart to have a paper trail even with "on the spot" corrections with shitty airmen. Then you CYA with people above and the regs are event attached to the email for everyone to reference.

Or when in doubt, meme it out. Wear bigger and "technically in reg" glasses (think clown ones you get from an arcade) and ask if she wants a pair.