Here we have a beautifully curvaceous 1962 IWC Automatic Cal. 8531 “Calatrava”, reference R 647A — a particularly desirable example thanks to its rarer “Jumbo” 36.5mm stainless-steel case. The case is a masterclass in early-60s IWC restraint: brushed and polished finishing throughout, slim polished bezel, and those wonderfully curved, drilled lugs that help it sit flat and comfortable on the wrist. Measurements are 43mm lug-to-lug and approximately 10.5mm thick, with a neat unsigned crown for easy grip which in our opinion is original as not all were signed on these earlier pieces.
Up top, a domed crystal (with cyclops magnification) draws the eye to a crisp sunburst silver dial. An outer ring of minute pips frames applied, faceted baton hour markers that catch the light as you move your wrist, while elegant slim Dauphine hands and a tapered seconds hand keep everything sharp and dressy. At 3 o’clock, a framed date window adds everyday practicality without disturbing the symmetry, while the dial is signed in IWC’s distinctive script and finished with “Automatic” above 6.
Inside is IWC’s Calibre 8531 (21 jewels), featuring the brand’s celebrated Pellaton winding system — Albert Pellaton’s 1950 innovation that efficiently converts the rotor’s bi-directional motion into stored energy at the mainspring. The watch is paired with a well-suited aftermarket 18mm leather strap and pin buckle.
Extra Points
In 1867 Florentine applied for a European passport with the dream of creating watches using the American system of Watchmaking. This system was taken from the Federal Armories at Springfield and Harpers Ferry. Where armaments needed high precision interchangeable parts. This was perfect to use in watchmaking and Florentine was a pioneer in introducing it to the Swiss. In 1868 Florentine and Charles Kidder ended up in Schaffhausen Switzerland. Originally called the company F. A Jones & Co which was later changed to IWC International Watch Company. In 1876 Florentine returned to the USA where he retired and sadly passed away in 1916. The spirit which he spent a lifetime perfecting carries on today in the modern IWC watches.
This watch has been fully serviced in our on-site workshop and comes with our 12 month, non-waterproof service cover.
What we think
This is one of those IWC’s that quietly makes a lot of “obvious” modern watches look a bit shouty. In the metal it’s all about restraint: a clean, sunburst silver Calatrava-style dial, sharp applied batons, and elegant Dauphine hands that catch the light without ever turning flashy. Then there’s the case—at 36.5mm it’s a rare “jumbo” size for the early 1960s, and that extra presence (plus the gently curved, drilled lugs) makes it wear far more like a contemporary daily watch than most vintage dress pieces. Add the framed date with cyclops at 3 o’clock and you get that satisfying “calendar watch” practicality, but executed in a very IWC way—understated, architectural, and brilliantly legible.
Condition matters hugely with these, and this example being near-mint is a big deal. With vintage IWC, crisp case lines and a clean, correctly aged dial are everything; when they’re right, the watch feels expensive in a way that photos don’t always capture. This one has that “kept, not merely owned” vibe—exactly what you want in a 1960s automatic dress watch.
From a value-for-money angle, it stacks up surprisingly well against the obvious alternative in this size/date bracket: the Rolex Datejust 36. A modern Datejust 36 (ref. 126200) sits around the mid-£6k range at retail, while a fluted/Jubilee-style Datejust (ref. 126234) is typically around the low-£8k mark. The Datejust is an icon (and the market treats it that way), but you’re also paying for that recognition and liquidity. This IWC offers a different kind of appeal: rarer on the wrist, more “insider” than status symbol, and powered by one of IWC’s most historically important automatic families—the Pellaton-winding era that collectors genuinely care about. In other words: if you want the best watch rather than the most recognised watch, this is a very persuasive argument.
It’s also worth sanity-checking it against modern IWC pricing, because that’s where the value really lands. Today, getting into a new IWC with automatic + date typically starts around the £4k–£5k level (for example a Portofino Automatic 40 at £4,300, or a Pilot’s Watch Mark XX around £4,800 depending on spec). That’s for a current-production watch (with warranty and modern water resistance expectations), but it does put this 1962 piece into perspective: you’re getting near-mint condition, a genuinely collectible “jumbo” vintage case, and a landmark IWC automatic architecture—often for money that sits uncomfortably close to (or below) the cost of a brand-new entry-level IWC, and materially less than a new Datejust.
Net: if you like classic design, want a true early automatic calendar from a top-tier manufacture, and you’d rather have something quietly special than universally recognisable, this is a seriously compelling buy.
Spec Stuff
Ref :R 647A
Serial : 1942####
Movement : Automatic IWC Cal. 8531
Age : 1961/1970 Specific Age : Circa 1962 Case Size : 36.5mm Case Thickness : 10.5mm Lug to Lug : 43mm Lugs : 18mm Condition : Pre-Owned Box & Papers : No Case Material : Stainless steel Service History : 12-Months NON-Waterproof Warranty
1962 International watch co Ref. R 647A - Iwc Cal.8531 in near Mint condition automatic large wristwatch
