IWC Calatrava R820A C.8541 "Jumbo" 36.5mm 1970

A beautifully example of the IWC Calatrava Ref. R820AD, affectionately known as a “Jumbo” for its generously sized 36.5mm case—an uncommon diameter for late-1960s dress watches. Produced in 1970, this understated piece captures the elegance of Swiss watchmaking from the golden era. It features a crisp silver sunburst dial, a screw-down caseback, and the iconic fish-logo crown. Professionally polished to near mint condition, it's a highly collectible piece you will rarely see on the market today.

Housed within is IWC’s highly regarded in-house automatic movement, the Caliber 8541B, equipped with the Pellaton winding system and whats known to be IWC's epitome of mechanical movements right before the Quartz crisis. Freshly serviced and keeping excellent time, this is a clean, refined vintage dress watch ready for daily wear or special occasions. Not to mentioned we have the entire movement laid out for all to see in the image above, a true testement to our transparency here at Montre D'or

DIAL:

• Original silver sunburst dial in outstanding vintage condition

• Applied IWC logo and printed "International Watch Co. Schaffhausen" script

• Sharp dauphine hands and faceted baton hour markers accross the dial

• Applied minute marker dots circling the dial's periphery

CASE:

• Gorgeous jumbo sized case with beautiful mirror and brushed faceted lugs

• 36.5mm diameter (without crown) / 45.0mm lug-to-lug / 11.5mm thickness

• 3-body construction with screw-down caseback

• Professionally polished with sharp faceted lugs preserved

• Original IWC-signed fish logo crown at 3 o'clock

CASEBACK:

• Screwdown caseback with a mix of sharp radial brushing and polished edges

• Comes with plastic protective sticker as shown, with a fresh gasket installed

MOVEMENT:

• IWC Caliber 8541B – Automatic with Pellaton winding

• Date set by moving minute hand between 9pm and 12am repeatedly

• 19,800 vph / 40-hour power reserve / 23 jewels

• Last Service: January 2026

• Accuracy: -2.0s/day

STRAP & BUCKLE:

• Handmade black Crocodile leg leather strap, 19mm lug width

• Aftermarket IWC-signed stainless steel buckle

AFTERCARE PACKAGE:

• Comes with a black wooden box + silica gel

• Complimentary PolyWatch crystal polishing kit (for acrylic crystal)

• 6-month warranty (covers non-user damage only)

• Guarantee Certificate with full service details included

• Access to our exclusive post-warranty repair services

• 7-day return policy for peace of mind

SPECIFICS

Maker: IWC

Model: Calatrava

Year: 1970

Case Material: Stainless Steel

Reference: R820AD

Case Serial Number: 1916425

Movement Serial Number: 1907291

Caliber: IWC Cal.8541B

Power Reserve: 40 hours

Accuracy: -2.0s/day

Diameter: 36.5mm

Lug to Lug: 45.0mm

Lug Width: 19.0mm

Thickness: 11.5mm

Lume: NIL

Strap: Black Crocodile leather strap

Buckle: Aftermarket IWC signed buckle

Box and Papers: NIL, Wood presentation box provided

Movement Type: Automatic

Crystal: Original IWC domed acrylic

Crown: Original IWC-signed fish logo crown

Last Service: January 2026

Free express tracked shipping with signature upon delivery. Delivery within Singapore in 1-2 working days. International shipping may take 2–12 working days depending on destination. Do note respective custom duties might apply which includes the recent US tariffs and are the buyer's responsibility.

Do note that for US bound shipments the PolyWatch polishing kit will not be included in order to mitigate customs delay due to new customs requirements

Countries that we do not ship to: Algeria, Nepal, Pakistan, Russia, Vietnam, Iran

This is a vintage timepiece and water resistance is not guaranteed. Please avoid contact with water or moisture. Store the watch with dry tissue or silica gel to preserve its condition. We are not liable for water damage post-purchase.