The smartwatch market is crowded. The smart ring market is just getting started, and most of the early entries have made the same mistake: they've built miniature smartwatches and crammed them into a ring form factor.
The Forge Core takes a different approach. It's not a watch without a screen. It's a purpose-built health sensor that happens to be shaped like a ring.
Why a Ring?
The finger is one of the best places on the human body to measure cardiovascular signals. The arteries in your fingers are close to the surface, blood flow is consistent, and there's minimal interference from tendons and muscle movement. That's why pulse oximeters, the clip-on devices hospitals use, go on your fingertip.
A ring sits on the finger 24/7 without the bulk, weight, or social friction of a watch. You don't take it off to type. You don't take it off to shake hands. You don't take it off to sleep. And because it has no screen, there are no notifications pulling your attention away from what you're doing.
For tradies, this matters. A watch on a wrist can catch on scaffolding, get smashed by a falling tool, or interfere with gloves. A ring sits flush against the finger, protected by the natural curl of the hand.
Titanium Alloy Construction
The Core's outer shell is titanium alloy, the same family of materials used in aerospace fasteners and surgical implants. Titanium offers an exceptional strength-to-weight ratio: the Core weighs just 6 grams in size 10, yet it's scratch-resistant enough to survive daily contact with steel, concrete, and tools.
The finish is a polished glossy black that looks like a standard men's ring. There's no visible branding on the exterior, no LED indicators, and no buttons. From the outside, it's indistinguishable from jewellery. The technology is entirely on the inside.
Sensor Array
Flip the Core over and you'll see the sensor window: a cluster of optical sensors and a temperature sensor embedded in the inner surface. These include:
Heart Rate (HR): Continuous optical PPG monitoring, sampled every few seconds during the day and continuously during sleep. The finger's vascular density means the Core often achieves more consistent readings than wrist-based sensors, especially during movement.
Heart Rate Variability (HRV): The time variation between heartbeats is one of the most reliable indicators of autonomic nervous system balance. Higher HRV generally correlates with better recovery, lower stress, and higher readiness. The Core measures HRV during sleep when readings are most stable and meaningful.
Blood Oxygen Saturation (SpO₂): Measured via red and infrared light absorption through the finger's capillary bed. Useful for detecting altitude effects, sleep-disordered breathing patterns, and general respiratory health trends.
Skin Temperature: A dedicated thermistor tracks skin temperature trends over time. This isn't a clinical thermometer. It is a trend sensor that can flag deviations from your personal baseline, which may indicate illness onset, hormonal cycles, or recovery status.
Battery and Charging
The Core delivers 4–7 days of battery life depending on usage patterns. Sleep tracking, continuous heart rate, and periodic SpO₂ checks fall within the 7-day range. Adding frequent HRV snapshots and temperature logging brings it closer to 4 days.
Charging uses a magnetic cradle. Drop the ring in, and it snaps into alignment. Full charge takes approximately 90 minutes. The charging case is compact enough to fit in a pocket or toolbox.
Water Resistance: 5 ATM
The Core is rated 5 ATM, which means it's tested to withstand pressure equivalent to 50 metres of static water. In practical terms: you can swim with it, shower with it, wash your hands aggressively, and get caught in a downpour without concern.
It's not rated for scuba diving or high-pressure water jets (that's what the Genesis is for), but for everyday water exposure, the Core is fully sealed.
Sizing: Get It Right
A smart ring only works if it fits properly. Too loose, and the sensors lose contact with your skin, and readings become unreliable. Too tight, and it's uncomfortable, especially when your fingers swell in heat or after exercise.
The Core is available in sizes 6 through 13. We strongly recommend using our sizing guide before purchasing. The ideal fit is snug enough that the ring doesn't spin freely, but loose enough that you can slide it over your knuckle without force.
Your ring size can vary by 0.5–1 size depending on time of day, temperature, hydration, and activity level. We recommend measuring in the evening when fingers are typically at their largest.
Who It's For
The Forge Core is for people who want health data without a screen on their wrist:
- Tradies and manual workers who can't or don't want to wear a watch on site but still want heart rate and sleep tracking.
- Athletes who want 24/7 HRV and recovery tracking without the bulk of a watch during training.
- Anyone who values discretion. The Core looks like a ring, not a gadget.
- Genesis owners who want the full Forge ecosystem. Watch on the wrist for active tracking, ring on the finger for passive 24/7 monitoring.
The Core doesn't try to replace a smartwatch. It does something different: it disappears into your life and quietly collects the data that matters most.