The90 Gem puts separate UVA and UVB readings on a necklace
The discounted pendant comes with account binding, a special charger and several accessories still waiting for a ship date.
A weather forecast can’t follow you under an umbrella. A pendant can, provided you haven’t tucked its sensor under your shirt and given it a completely different afternoon.
The90 Gem puts a UV sensor in jewelry, with separate readings for UVA and UVB. The useful gadget idea is local measurement: light arriving where the sensor sits, instead of a regional forecast. The necklace takes a shine to sunlight, quite literally, and a change of position gives its sensor something different to register.
The company also wraps those measurements in a daily score and wellness language. Its own disclaimer says vitamin D is estimated using exposure and a skin profile. It doesn’t measure blood levels. The90 says the product doesn’t replace sunscreen or medical advice. A dashboard can display a biological estimate with exactly the same visual confidence as a sensor reading, so the distinction deserves more prominence than a tiny footer.
The shop currently lists the Gem at $149, reduced from $249. Shipping is US-only, free for standard delivery, with dispatch from California in one to two business days. Those are today’s storefront terms, rather than a new launch announcement or a promise that the discount lasts.
It has company. Sun-a-wear sells a solar-powered clip-on tracker, while SunSense One displays readings on its own screen. Both make the buying decision less about whether UV can be measured on your body and more about how you want to wear and read the sensor.
| Purchase detail | The90 Gem | sun-a-wear UV tracker | SunSense One |
|---|---|---|---|
| Listed price | $149 sale; $249 regular | $89 USD | 998 NOK |
| Reading interface | Phone app; separate UVA/UVB measurements claimed | Phone app; UV index specified | LCD; UV dose and UV index |
| Power | Claimed 7+ days; proprietary magnetic charger | Solar; no charging | Replaceable CR2032; up to 3 years claimed |
| Wear format | Pendant with removable core | Clip | Clip |
| US delivery information | US-only; California dispatch | US included in shipping offer | US absent from listed delivery countries; contact maker |
Prices and specifications above come from each manufacturer’s linked product page. Both rival pages display a sold-out label as well as an add-to-cart control, so their live availability needs confirmation before treating either as a ready replacement. The chart compares designs; it doesn’t declare an accuracy winner.
The Gem manual adds the sort of detail that tends to disappear beneath a lifestyle photograph. The sensor window needs to face outward and stay clear of thick sunscreen or lotion. Jewelry that measures light still needs a clear view of it. The optional hat clip and bag tag remain in development on the shop’s FAQ, without announced dates. The hat clip would be useful for someone who dislikes necklaces, but the company has given that buyer no date to plan around.
The90 calls the account binding “Owner Lock.” That may discourage someone from claiming a lost sensor, but it also puts an app step between the original owner and the next one. A used necklace now comes with the kind of handover procedure once reserved for a phone. Naturally, jewelry now has an account handover to remember along with the charger when passing the pendant to someone else.
The water instructions deserve caution too. The manual’s permitted-use text mentions showers, while the shop tells buyers to remove it for showering or swimming. The safer reading of those conflicting pages is to follow the shop’s narrower restriction. A water-resistance figure doesn’t erase the manufacturer’s own exclusions.
Wearable dashboards could become more useful as they show where a measurement ends and an estimate begins. The practical test here is whether the local readings help someone understand changing light conditions without confusing a score with a lab result. The marketing covers a lot of ground; the photodiode has a much smaller view.
The umbrella still gets its own reading.