The UV-tracking Gem made me rethink how sunlight affects my health, not just my appearance

The Gem is a wearable UV tracker that prompted its reviewer to reconsider how sunlight affects health, beyond visible sunburn or skin ageing. At an outdoor gathering, the device warned of rising UV exposure while the reviewer was sitting in shade; they later felt unwell and discovered that one of their medicines increased sensitivity to heat. The tracker did not diagnose the cause, but encouraged them to look into recurring symptoms and take more care outdoors.

The $249 necklace measures UVA and UVB separately, and its app uses those readings and an optional skin profile to estimate factors such as vitamin D production and cumulative exposure. Those figures are predictions, not direct measurements of the body’s response, and the reviewer found some estimates more useful than others. The pendant is lightweight, lasted about a week per charge and helped the reviewer better understand that shade does not eliminate UV exposure.