The data powering the next generation of skincare.
The proprietary metric
Meet your Sun Score.
Like a sleep score for your skin’s life in the sun. Every day, The90 algorithm turns your real UV exposure into one clear number that’s personal to you, built from five signals working together.
Today
Five signals. One number that’s only yours.
Personal Skin Profile
Your type, genetics, and sensitivities are the baseline your Score is calibrated to. The UV index says the same thing to everyone. Yours only speaks to you.
Skin Aging Zone
Tracks the UVA hitting your skin through the day and as it accumulates over time. UVA doesn’t burn; it ages. Now you can see it.
Time Protected
Measures how much of your day you’re actually covered vs. exposed, then tells you the moment it’s time to reapply.
Vitamin D Production
Estimates the benefit you’re getting from daily light, so you get enough to thrive without tipping into damage.
Circadian Rhythm
Rewards the morning and evening light that sets your energy, mood, and sleep, the light that’s actually good for you.
More in the app.
The Sundial
Live UVA and UVB intensity, streaming in real time.
Skin Aging Zone
Your cumulative UVA exposure, tracked across hours, days, and months.
The Burn
A personalized countdown to your daily limit.
No subscription required.
Your Gem comes with the full Sun Score app: every core feature you need to start owning your light, no monthly fee.
Compatibility
iOS 15.0+ · iPhone 8 and newer. Android 9.0+ · Bluetooth 5.0 required. BLE connection to The Gem.
Privacy
Your skin data is yours. We use it to power your personalization and never sell it. Most processing happens on-device. Cloud sync is opt-in and encrypted.
Is there a subscription or monthly fee?
No. Your Gem comes with the full The90 app and every core feature, with no monthly fee to read your own light. You buy the sensor once.
What does The Gem actually measure?
It reads the UVA and UVB reaching your skin, separately and in real time, then turns the day into a single Sun Score from 0 to 100. Along the way it tracks the light you want, like your morning circadian light and your estimated vitamin D, and the exposure you want to manage, like the UVA that ages your skin.
Do I have to wear it as a necklace?
It comes as a jewelry-grade pendant on a matching gold or silver chain, so you can wear it out of the box. The Gem is also a removable core, so it can move into new ways to wear it as they launch, including a hat clip and bag tag on the way.
How is this different from the UV Index or my weather app?
The UV Index gives one number for a whole city and says the same thing to everyone. The Gem measures the light actually hitting your skin, separates the aging rays from the higher-energy ones, and reads it against your personal skin profile in real time. It is the difference between a forecast and your actual day
Can I wear it in the water?
Rain, sweat, and a quick rinse are all fine. The Gem is water resistant to 1 meter for 30 minutes, so leave it off for the pool, the shower, hot tubs, and saunas.
What if it is not for me?
Try it for 30 days. If it is not right, send it back for a full refund, and every Gem is covered by a 1-year warranty. Free shipping, dispatched from California within 1 to 2 business days, currently within the US.
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