The Audemars Piguet Royal Oak Offshore Tourbillon Chronograph 25th Anniversary and Royal Oak Offshore Selfwinding Chronograph are three new, pre-SIHH 2018 references that we’ll see in stores next year, when AP is celebrating the 25th anniversary of its Royal Oak Offshore line. When Audemars Piguet unveiled the first Royal Oak Offshore some 25 years ago, I…