Classic B&L Ray Ban sunglasses

25+ year old Ray Bans. I received this as a pass down gift from my aunt she hasn't worn it in the 25 years she owned it, it was worn before that tho by her late husband of a very very long time ago she is 70+ now. The Ray Ban is orginal and in very good condition It has signage on each side reading -SIGNET ,and on the other side -B&L RAY-BAN U.S.A On the lenses is marked BL very finely on the left side of each Lens and the trade mark white Ray-Ban singnage on right Lens. And ontop of the nose piece B&L RAY-BAN U.S.A I would like to know the value of this piece? The sunglasses needs a clean but I'm not willing to clean because i don't know what products to use In case of me damaging it etc.