Hublot Spirit of Big Bang Tourbillon 5-Day Power Reserve Sky Blue Ceramic 42mm 645.EX.5123.NR

The Hublot Spirit of Big Bang Tourbillon 645.EX.5123.NR is a striking testament to the Geneva manufacture's philosophy of fusing cutting-edge materials with high-complication watchmaking. Introduced as part of the Spirit of Big Bang line — itself a refined evolution of the iconic tonneau-shaped Big Bang silhouette — this 42mm reference translates Hublot's bold design language into a wearable, wrist-friendly format without sacrificing any of the mechanical theatre that defines the collection. The sky blue ceramic case gives this particular reference an identity all its own, separating it unmistakably from the broader Spirit of Big Bang family.

Ceramic has become one of Hublot's signature case materials, and on the 645.EX.5123.NR it is used with exceptional coherence: both the barrel-shaped case and the bezel share the same sky blue ceramic composition, creating a seamless, monochromatic visual statement. Ceramic is prized by collectors for its featherlight feel relative to steel, its near-immunity to everyday scratches, and the depth of color it retains over decades of wear. The sky blue hue in particular is a rare and evocative choice, evoking open skies and giving the watch an airy, almost ethereal personality that contrasts beautifully with the mechanical complexity visible beneath the dial.

The skeleton dial is where the Spirit of Big Bang 645.EX.5123.NR truly commands attention. By stripping away all non-essential material from the movement architecture, Hublot invites the wearer — and anyone nearby — to observe the tourbillon cage rotating in real time, the hand-finished bridges catching available light, and the intricate choreography of gears and levers that constitute a high-complication movement. The openworked aesthetic is consistent with Hublot's longstanding commitment to what the brand calls the Art of Fusion: the deliberate, creative combination of tradition and innovation.

Powering the watch is a manual-winding tourbillon movement endowed with a 5-day, or 120-hour, power reserve — a substantial reserve that speaks to the engineering ambition behind this reference. A tourbillon, first patented by Abraham-Louis Breguet in 1801, houses the escapement and balance wheel within a rotating cage designed to average out the positional errors caused by gravity, and remains one of the most respected and technically demanding complications in watchmaking. The 5-day autonomy means the wearer can set the watch on Friday evening and return to it Monday morning without fear of finding it stopped — a genuinely practical virtue in a complication that also serves as pure horological theatre.

On the wrist, the Spirit of Big Bang 645.EX.5123.NR strikes a balance that larger Hublot references sometimes sacrifice: at 42mm the tonneau case sits confidently without overwhelming the wrist, making it suitable for a broader range of wearers and occasions. The fabric and rubber strap completes the picture with the casual-luxury contradiction Hublot has always championed — technical textile woven for comfort and visual texture, bonded to a rubber lining for durability and sweat resistance, and secured with a deployant system designed to keep the watch secure through an active day.

Bizak & Co. is proud to offer this reference brand new, meaning it arrives in full, unworn condition with all manufacturer packaging. Buying from Bizak gives collectors access to expert guidance, transparent pricing, and the confidence that comes from purchasing through an established luxury watch dealer. Whether you are adding a first tourbillon to your collection or seeking a statement sky blue ceramic piece to complement an existing roster, the 645.EX.5123.NR represents a compelling case for one of contemporary watchmaking's most visually distinctive high complications. Reach out to the Bizak & Co. team online to enquire, reserve, or purchase this watch today.