The AudemarsPiguet perpetual calendar watches were developed back in 1981, starting to appear in the Royal Oak series in 1984 with the reference 5554 known as the non-leap year version. First conceived in 1998, the second generation with the reference 25820 has then evolved with an intergraded leap year indication, and was available with five dial variants in stainless steel, two dial variants in 18K yellow gold, two in platinum, three in stainless steel with platinum, and perhaps the most coveted of them all, a tantalum and rose-gold version, a tantalum and yellow gold version, and the king of all Royal Oak Perpetual Calendars – the tantalum and platinum version. According to our research, the present platinum with Tuscan dial configuration masterpiece is said to have only 12 pieces made, which makes this piece one of the rarest and unusual Royal Oak perpetual calendars ever appear in auctions. Hong Kong Important Watches Sale | 13 Oct Estimates: HK$800k – 1.6m/ US$103k – 205k Vis...