I've answered this question many times before, and unfortunately, when I sees an issue for so many years, and so many times, sometimes, the eyes glaze over and you miss it.
From (at least) 2004:
"As of May, 2004, all Royal Oak models, with the exception of the mid and full sized Offshore models (complete calendar, chronograph) use gold screws/bolt and nut.
I've been told in the past that due to the unique construction and assembly of case, bezel, and back, as well as the gaskets, of the mid and full sized Offshores, which are different than the RO case construction, assembly requires high pressures which require steel screws/bolts/"nuts"
Thus, these parts on the mid and full size Offshore models are made of steel.
Also a few comments regarding "screws" vs nuts and bolts -
According to a good friend inside AP, the French term for the bezel side fastener is visse hexagonal
which apparently is normally translated as "hexagonal screw"
HOWEVER, specialized "lingo" terms are often translated differently than common usage terms.
The rear (back) fasteners are called ecrou
but again, inside AP, they are referred to as "back screws" (and again, this is AP's term, therefore it is correct in this case - pun intended - to call them screws, since we are talking about an AP product and design; HOWEVER, in most English contexts, they would be termed bolt and nut)
Of course, since the lingua franca
of most of the high horology (or should that be, haute horlogerie?
) world is French, why don't we just use "visse hexagonal"
Merci beaucoup, Majeste!
(for more on this subject, click here -
thread on the main AP discussion forum on this subject
Personally, for common English usage, I would lean toward nut and bolt)
There is a reason we are considered THE authoritative independent source on all matters AP, not a bad idea to check here for answers first, in our archives.
We have dispelled many a widely held myths, including the (incorrect) supposed existence of a cal. 2120 with second hand, mistakenly identified as cal. 2122. Again, THIS DOES NOT EXIST (2120 with second hand)
We've even corrected ourselves, when we were wrong (eg, the supposed existence, now confirmed incorrect, of a first series non-alpha leading 1000 pieces in the initial Royal Oak model line launched in 1972. Steel versions started with the leading alpha character; only SA models - steel and gold - were released in cases without leading alpha character.)
Again, sorry about that, I should have caught that mistake when I proof read the article.
"A Purist does not believe in gilt by association. Respect, AND disdain, have to be earned..."