Patek Philippe Genuine Ar Coating

[Linder]

Does anyone know how PP applies their AR coating? I have spent plenty of time at my local AD but cannot figure out if the coating is applied to the inside, outside or both sides. Does anyone know?

I have purchased a genuine strap for EL's 3919 and am now looking to AR coat it if I could just figure out how it needs to be coated, LOL. I have made good friends at my local AD and afterwards, I plan to acquire a set of springbars for accurate gold color reference. Then bring on the 18K yellow gold replating!

If anyone has advice for any of these steps or if you could point me in the right direction to get the plating done, I would greatly appreciate it as well.

Thank you!