Modem and Retinaa propose QUARTZ — a signet ring that functions as a wearable cryptographic ledger, activating trust through the oldest technology available: the in-person handshake.
A Gartner survey found that 62% of organisations reported experiencing a deepfake attack in the past twelve months. The statistic is the opening condition of the QUARTZ project, but it is not the project's real subject. Its real subject is older and more fundamental: how does trust work, and where does it live? For millennia, trust was anchored in the physical body — in the act of meeting in person, in the offered hand, in the visible signs of identity. QUARTZ is a design proposal that asks what happens if we take that ancient infrastructure seriously and rebuild it with contemporary cryptographic tools.
The ring, designed in collaboration between Amsterdam-based Modem and Swiss studio Retinaa, contains enterprise-grade security hardware within a Swiss quartz-stone signet face: cryptographic keys stored on-ring, paired uniquely to its wearer via near-infrared finger-vein biometrics, with a real-time pulse sensor to prevent spoofing. Each stone carries a unique natural structure recorded on a blockchain-based digital certificate — a Physical Unclonable Function that makes the object itself irreplicable. The ring is not the metaphor. It is the mechanism.
Trust is activated by meeting in person. When two QUARTZ wearers shake hands, the rings communicate via NFC at close range — an intentional, tactile, physical act — to generate a unique Shared Secret: an encrypted bond between two specific people that can then be verified remotely through zero-knowledge proofs without ever exposing the underlying data over the internet. "The QUARTZ protocol is built on what remains true when everything else can be synthesised," says Scott Kooken, Research and Design Director at Modem. "Biology binds the ring to a living person. Physics binds trust to a real encounter. Mathematics makes that trust portable to the digital realm."
The project situates itself in a long history of objects that materialise trust: the signet ring as legal seal; the handshake as witnessed contract; the bow as territorial greeting. Carl Guilhon, Co-Founder of Retinaa, frames the shift clearly: "In the age of AI, seeing is believing no longer holds. QUARTZ asks what happens when we stop anchoring trust solely in the online world — and bring it back to the physical." Whether as a functioning protocol or a design speculation, QUARTZ is a proposal about which direction to look when the digital world becomes unverifiable: not further in, but back out.
