Royal Tunku Ismail Ibni Sultan Ibrahim spotted wearing a Patek Philippe

The Crown Prince of Johor, Tunku Ismail Ibni Sultan Ibrahim, has been spotted wearing the Patek Philippe Nautilus Travel Time Chronograph in stainless steel, Reference 5990/1A — a watch that sits at the technical apex of the Nautilus collection and remains one of the most coveted complications in modern watchmaking.

First introduced in 2014, the 5990/1A houses Calibre CH 28-520 C FUS, a self-winding flyback chronograph movement with a column wheel, horizontal clutch, and an integrated travel time function that displays a second time zone via a jumping hour indicator. The movement beats at 28,800 vph, offers approximately 45 hours of power reserve, and is finished to Patek Philippe's exacting standards with Geneva Stripes, beveled bridges, and perlage on the base plate. The case measures 40.5mm in stainless steel with the Nautilus's distinctive porthole-inspired bezel and integrated bracelet — a form language drawn directly from Gerald Genta's original 1976 design brief.

From a collector's perspective, the 5990/1A occupies a particularly compelling position. It delivers two of horology's most desirable complications — a flyback chronograph and a dual time zone — in the steel Nautilus format, which has historically commanded the strongest premiums in the grey market. Unlike the more commonly spotted 5711 or 5726, the 5990 demands that its owner appreciate the full depth of its movement architecture. Production numbers are deliberately limited, and steel availability through authorized dealers has been essentially nonexistent for years.

Tunku Ismail is no casual watch enthusiast. The Crown Prince maintains a publicly visible collection that spans Patek Philippe, Richard Mille, and beyond, and has repeatedly demonstrated a preference for watches with genuine mechanical substance rather than simply status-driven references. His choice of the 5990/1A reflects exactly that sensibility — this is a watch that rewards knowledge as much as it does wealth.

On the current grey market, the 5990/1A in steel trades at a significant premium over its official retail price, which sits at approximately £42,370 in the United Kingdom. Demand consistently outpaces supply, and the reference shows no signs of cooling among serious collectors worldwide.