IWC Schaffhausen Portuguese Perpetual Calendar Ref. IW5021 & Ref. IW5023

IWC Schaffhausen expands their Portuguese Perpetual Calendar with two new variants in red gold and two in white gold increase the variety of models on offer. This perpetual calendar watch is powered with an IWC – manufactured large movement from the 50000-calibre family with a seven-day power reserve.

This is an ideal combination for a complicated watch with calendar indications displaying the date, day, month, year in four digits and perpetual moon phase. The watch displays advance completely autonomously, mechanically programmed and synchronized with one another. Save for a leap day correction that becomes necessary in February 2100, this continues uninterrupted and without any intervention on the part of the wearer, who simply needs to input the required kinetic energy via the highly efficient Pellaton winding system of the automatic movement when wearing the watch.

According to the complicated Gregorian calendar, which always assures years of almost constant length, the leap day that would be due to occur is absent at the end of February in the year in question, 2100, and this will necessitate an adjustment by a watchmaker.

It might thus be appropriate to ensure that one’s grandson or great-grandson is aware of this fact. In that far-off year, incidentally, the century slide at the end of a long transmission chain will also be advanced by a couple of millimetres, and the numeral “21” for the next hundred years set in the display window in place of the currently indicated “20” to make the year display complete.

IWC Portuguese Perpetual Calendar 18 ct red gold version with black dial, Reference IW502122
IWC Portuguese Perpetual Calendar 18 ct red gold version with black dial, Reference IW502122

The beguiling new eternity in the form of the Portuguese Perpetual Calendar retains its two familiar faces: one model of this watch is equipped with a quasi-universal hemisphere lunar display (Ref. 5021), in which the miniature model of the Earth’s satellite is pictured twice. Exactly as the phases of the moon appear when viewed from the northern or southern hemisphere – that is to say reversed. This distinctive optical feature has to do with the visual angle and the different point of observation.

The number of days remaining until the next full moon can also be read precisely on a supplementary countdown scale in this model. The new Portuguese Perpetual Calendar in 18 carat red gold with hemisphere lunar display (Ref. 5021) differs from the previous rose gold model through the rather warmer hue of the case material.

The second new model, the white gold variant with a midnight blue dial and silver-plated highlights, for example for the seconds subdial or on the moon disc, presents a particularly attractive side as regards colour.

IWC Portuguese Perpetual Calendar 18 ct white gold version with midnight blue dial, Reference IW502121
IWC Portuguese Perpetual Calendar 18 ct white gold version with midnight blue dial, Reference IW502121

The simultaneous display of the two moons functions as follows: it is not the moon disc itself that moves, but an engraved disc representing the globe with two circular cut-outs set against a silver-coloured background, which carries two blue circular surfaces in a horizontal plane. In this way, the moon in the southern hemisphere is shown mirror-inverted or laterally reversed in relation to the moon in the northern hemisphere.

A second version of the Portuguese Perpetual Calendar is available with the classic cut-out moon phase display when observed from the northern hemisphere (Ref. 5023).

IWC Portuguese Perpetual Calendar 18 ct Red Gold Version with Silver-Plated Dial, Reference IW502302
IWC Portuguese Perpetual Calendar 18 ct Red Gold Version with Silver-Plated Dial, Reference IW502302

The Earth’s satellite waxes onto this miniature stage from the left behind the semicircular setting becomes visible in the middle as a full moon and wanes on the right side behind the second semicircle. It is accompanied on the moon disc by small raised stars.

The two new models with the representation of the moon behind a setting are now also housed in the 44.2-millimetre case of their sibling models (Ref. 5021). These are the variant in 18 carat red gold with a silver-plated dial, solid red gold appliqués and a red gold-plated moon surrounded by small stars, and a highly discreet model in 18 carat white gold with rhodium-plated appliqués and a slate-coloured dial.

IWC Portuguese Perpetual Calendar 18 ct White Gold Version with Slate-Coloured Dial, Reference IW502303
IWC Portuguese Perpetual Calendar 18 ct White Gold Version with Slate-Coloured Dial, Reference IW502303

As far as the key astronomical indication of the Portuguese Perpetual Calendar, the moon, is concerned, it is able to match the precision of scientific instruments: in these watch models – and in these alone – the gearing has been modified, thanks to the available space, so as to permit the moon cycle to be displayed with unprecedented accuracy.

A tiny residual error of 12 seconds per lunar period (29 days, 12 hours, 44 minutes and 3 seconds) will add up to a deviation of just one day after 577 years.

Technical details

Model: IWC Portuguese Perpetual Calendar Ref. IW5021

Versions
Reference IW502122: 18 ct red gold with black dial and dark brown alligator leather strap, folding clasp in 18 ct red gold
Reference IW502121: 18 ct white gold with midnight blue dial and black alligator leather strap, folding clasp in 18 ct white

Functions
Perpetual calendar, perpetual moon phase display, hemisphere lunar display, four-digit year display and small hacking seconds

Movement
Calibre 51614
IWC-manufactured movement with Pellaton winding system
Breguet spring, rotor with 18 ct yellow gold medallion.
Beats: 21,600/h
Jewels: 62
Power reserve: 7 days (168 h)
Winding: automatic

Case, dial and strap
IW502121: 18 ct white gold with midnight blue dial and black alligator leather strap, folding clasp in 18 ct white gold
IW502122: 18 ct red gold with black dial and dark brown alligator leather strap, folding clasp in 18 ct red gold
Glass: sapphire, convex, anti-reflective coating on both sides
Back: see-through sapphire-glass back
Water-resistant: 3 bar
Diameter: 44.2mm
Height: 15.5mm

Model: IWC Portuguese Perpetual Calendar Ref. IW5023

Versions
Reference IW502302: 18 ct red gold version with silver-plated dial and dark brown alligator leather strap
Reference IW502303: 18 ct white gold version with slate-coloured dial and dark brown alligator leather strap

Functions
Perpetual calendar, perpetual moon phase display, cut-out lunar display, four-digit year display and small hacking seconds

Movement
Calibre 51613
IWC-manufactured movement with Pellaton winding system
Breguet spring, rotor with 18 ct yellow gold medallion
Beats: 21,600/h, Jewels: 62
Power reserve: 7 days (168 h)
Winding: automatic

Case, dial and strap
IW502302: 18 ct red gold with silver-plated dial and dark brown alligator leather strap, folding clasp in 18 ct red gold
IW502303: 18 ct white gold with slate-coloured dial and dark brown alligator leather strap, folding clasp in 18 ct white gold
Glass: sapphire, convex, antireflective coating on both sides
Back: see-through sapphire-glass back
Water-resistant: 3 bar
Diameter: 44.2mm
Height: 15.5mm

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