Dear All, I've had these Church's Chetwynds (Custom Grade) for a few years now and recently read about how Church's uses both Bookbinder Leather and proper Calf. Is anybody able to tell what kind of leather this is? The one on the left is unpolished (after a few months of wear) and the one on the right is polished. I bought them "slightly used" so I don't have a receipt to check on. Thank you!