Entrepreneur Riccardo Spagni spotted wearing a Jacob & Co

Riccardo Spagni, the South African-born software developer best known as the lead maintainer of Monero — the open-source, privacy-first cryptocurrency — has been spotted wearing one of the most extravagant complications in contemporary watchmaking: the Jacob & Co Astronomia in black gold, reference AT100.31.AC.SD.A, limited to a production run of just 18 examples worldwide.

The Astronomia is Jacob & Co's flagship haute horlogerie statement, and the Black Gold variant pushes the concept to its outer limits. The 47mm case is crafted from black gold — a material produced through a proprietary PVD or alloying treatment that yields the distinctive matte-dark finish — and houses the manufacture Caliber JCAM37, a hand-wound movement delivering 60 hours of power reserve. The complication architecture is what defines this watch: four arms rotate on a central axis once every 10 minutes, each carrying a distinct element — a triple-axis tourbillon that rotates on three axes simultaneously, a 1-carat magnesium-coated earth globe that spins on its own axis once every 60 seconds, a 288-facet Jacob-cut diamond serving as the sun, and the time display itself. The dial, in this reference, is set against a blue aventurine backdrop that deepens the celestial theatricality of the piece.

From a collector's perspective, the Astronomia occupies a rare space: it is neither understated nor remotely traditional, making it a deliberate, confrontational choice. The 18-piece limitation on the AT100.31.AC.SD.A places it firmly in ultra-rare territory, far beyond the standard Astronomia production references. For those who track Jacob & Co's escalating position in serious horological circles — the brand has collaborated with movement designer Luca Soprana and earned genuine respect for its in-house technical development — this reference represents a high watermark.

Spagni's affinity for the piece carries its own subtext. As the architect of a financial system built on anonymity and decentralization, wearing a watch that costs the equivalent of several hundred Bitcoin — and that makes no attempt whatsoever to be discreet — reads as a deliberate, perhaps ironic, flex. The Astronomia is not a watch you wear to pass unnoticed.

At £525,000 on UK list price, the AT100.31.AC.SD.A enters a tier shared by grand complication pieces from Patek Philippe and Richard Mille. Grey market data for an 18-piece limited Jacob & Co in black gold is scarce by nature, but examples have traded at or above retail given their scarcity and the sustained growth of the Astronomia family's secondary market profile.