The Gem tracks UV and costs $300 as a necklace

The90, the startup founded by former Fitbit executive Stacy Salvi, has launched The Gem, a pendant that tracks UVA and UVB exposure and costs $300. It is not a wellness Swiss Army knife, and it is not trying to be another AI trinket with a battery problem. It is a piece of jewelry with a very narrow job description, which is either refreshing or wildly expensive, depending on how much you care about sunscreen and sunlight.

The company’s pitch is straightforward. The Gem measures UV exposure in real time, turns that into guidance through its companion app, and wraps the whole thing in a necklace design aimed at women. Sun damage, of course, does not care who is wearing the pendant, but the styling probably helps The90 avoid the usual black-plastic-fitness-band problem.

What The Gem actually does

According to The90, the pendant goes beyond the broad UV index you see in weather apps by collecting live environmental data and translating it into personalized advice. That includes UV thresholds tailored to the wearer, reminders to reapply sunscreen, and suggestions for safer sun exposure windows. In other words: fewer generic weather warnings, more “you have had enough sunshine for today.”

• Tracks UVA and UVB exposure in real time
• Lets users build a skin profile in the app
• Offers sunscreen reapplication reminders and custom sun limits
• Works as a pendant-style accessory rather than a wrist wearable

The Gem price and launch offer

• Early buyer price: $200
• Regular price: $300

That puts The Gem in uncomfortable territory: high enough to compete with serious wearables, yet limited enough that buyers may wonder why a phone app and sunscreen bottle did not already do most of the work.

Recommended reading

Apple targets WWDC 2027 for privacy-focused smart glasses

Still, there is a larger trend here. Health wearables have been drifting toward narrower, more specialized use cases, especially as consumers grow tired of gadgets that promise everything and deliver notifications plus a charging cable. UV tracking is a sensible niche, and jewelry may be a smarter format than another screen-heavy device. Whether enough people want to pay premium accessory prices for sun awareness is the real test.

A niche product with a narrow runway

The Gem looks like an attempt to turn a practical health metric into something people might actually wear every day. That is the clever part. The awkward part is the bill. If The90 can make the case that constant UV awareness changes behavior, the pendant has a shot; if not, it risks becoming a very polished reminder that sunscreen already exists.