There are surprisingly few Tiffany-signed Audemars Piguet as relative to Rolex or Patek Philippe. Mostly, we see earlier and neo-vintage era Royal Oaks, with the occasional mid-century Calatrava. That's really about it, and even then the Royal Oaks are scarce and far between. This is a ref. 25589BA, otherwise known as the Day-Date Moonphase or 'Sartorial Owl' (I've only heard that twice but it tracks and is a great nickname). It happens to be one of the very few AP references where a handful were signed 'Tiffany & Co' on enamel, underneath a classic block font signature at 12.
1980s Audemars Piguet had a more classic idea of what a Day-Date should be, which included a moonphase, ultra-thin 33.5mm case (only 8mm tall), short curved lugs, white enamel dial (which often warms in age), blued steel day and date hands, and restrained fonts. It’s also just good fun to say you’re wearing a Day-Date upon inquiry and then produce this from under your sleeve. The 25589 was introduced as an alternative to the QP ref. 25657, sharing a similar case design but simplifying the complication. This came by way of an automatic caliber 2825, the same as in the Royal Oak Day-Date, based on a JLC ébauche. Because this watch is almost entirely enamel dial, with a very thin bezel, it does wear mil or two larger than its size would suggest.
It’s detail that differentiates special Royals Oaks consistently and AP's non-sporting models alike. The two lines at 12 each have their meaning. The Tiffany signature is a clear standout, making this watch something of a unicorn. The block font, or non-mixed, Audemars Piguet marks this dial out as an earlier production. This is a Day-Date, yes, but one focused on sheer elegance with all the 'look closer' detail one could want for.
