User Manual The90

SYSTEM OVERVIEW: THE MODULAR DESIGN

The90 Gem is a high-precision UV sensor designed for versatility. Your device consists of two distinct parts:

— The Gem: This is the removable, hexa-circle sensor module containing the UV sensor, 3-axis accelerometer, and Bluetooth chip.
— The Pendant: The primary Gold or Silver-hued Titanium housing for your Gem.

Assembly: To wear the Gem, snap it into the Pendant from back to front with the black quartz glass facing out. Ensure the small sensor window is at the top, closest to the bale (the loop where the chain attaches).

Future-Ready: The Gem is designed to be moved between different form factors. While you may have purchased it as a pendant, the modular "Gem" core is compatible with future official accessories, such as an upcoming Gem Clip.

GETTING STARTED

System Requirements

  • iOS: Version 16.0 or later.

  • Android: Version 12.0 or later.

    • Note: Android users must enable "Nearby Devices" and Location Services for pairing.

Initial Setup & Pairing

  1. Power On: Connect the Proprietary Magnetic Charger to a power source using the provided USB-C cable.

  2. Dock the Gem: Place the Gem onto the charger. Integrated magnets will snap it into the correct alignment.

    • Note: The Gem can stay in the Pendant to charge.  It does not need to be removed.

  3. Pairing Mode: Upon docking for the first time, place the Gem onto the Charger.  The charger LED will glow Blue. Open The90 App and follow the on-screen instructions.

Skin Profile: Complete your profile in the app. This is required for the Gem to calculate your personal Estimated Time to Burn and Zone Accumulation.

 THE PROPRIETARY CHARGER & INTERACTION

Because the Gem is buttonless, the Proprietary Magnetic Charger serves as your physical interface. When the Gem is docked, the entire device acts as a button when depressed down onto the charger.

Action

LED Feedback

Meaning

Connecting

Solid Blue

Device is ready to connect with the app.

Docking

Solid White (30s)

Charging has successfully been initiated.

Single Press

Green Flash

Status: Battery is fully charged.

Single Press

White Flash

Status: Device is still charging.

7-8s Hold

Amber Flash (1s) followed by Solid White

Hard Reset confirmed (Hardware restart).

Automatic

Solid Red

Error: Check docking alignment, USB power, or battery temp.  For more information about red light status, please see Battery Health Protocol.

Note on Hard Reset: This restarts the hardware if the device is unresponsive. It does not delete your data or unpair the device from your account.

WATER & ENVIRONMENTAL GUIDELINES

The Gem is engineered for an active lifestyle, but it is a precision electronic instrument. To maintain its integrity, follow these exposure standards:

Water Resistance Levels

  • Permitted: Your Gem is splash-proof and resistant to rain, the shower, accidental splashes, and sweat. 

  • Prohibited: Do not submerge the Gem or expose it to high-pressure water (e.g., power showers, diving, water skiing) or high-velocity water impact.

  • Thermal Warning: Avoid extreme heat, such as saunas, steam rooms, or hot tubs, as high temperatures can compromise the internal seals and battery.

Post-Exposure Maintenance

If your Gem is exposed to anything other than freshwater (saltwater, chlorine, or sweat):

  1. Remove the Gem from the pendant.

  2. Rinse both components briefly under a gentle stream of fresh tap water.

  3. Dry thoroughly with a soft, lint-free cloth before reassembling or placing on the charger.

    • Never place a wet Gem on the Charger.

Temperature Guidance

  • The Gem can be used between -20C - 60C (-4F - 140F) and can be charged between 0C and 45C (32F - 113F)

GEM QUARTZ & CASE CARE

Sensor Clarity: The Gem features a precision Quartz Glass face. Keep this window free of thick sunscreens, heavy lotions, or oils to ensure accurate UV data.

Surface Care: Wipe the sensor face and metal housing daily with a soft, lint-free cloth. Avoid abrasive cleaners or chemicals that may degrade the PVD finish.

BATTERY HEALTH PROTOCOL

To protect your One-Year Limited Warranty and maximize battery lifespan:

  • To prevent permanent battery degradation ("Deep Discharge"), do not allow your Gem to sit at 0% charge for more than 1 day.

  • Low Power Alerts: Dock your Gem as soon as you receive a notification from the app.

  • Storage: If not wearing for an extended period, charge the Gem to 100% at least every 6 months.  

If the red LED persists after charging for 1 hour and taking the Gem off and back on the Charger, then there could be an issue with the Gem battery (aka battery has decayed below the safe limit to recharge it).  Please reach out to support@the90.com for further assistance.

SECURITY & OWNERSHIP

The "Owner Lock"

Your Gem is bound to your account. If lost or stolen, a finder cannot "force claim" or factory reset the device using a physical button.

Gifting or Transferring

If you wish to give your Gem to another person, you must perform a Remove Gem Factory Reset from within the app settings. This initiates factory reset procedure, unbinds the hardware and prepares it for a new owner.

RETURNS & WARRANTY

30-Day Guarantee: Returns for a full refund (less shipping) are accepted within 30 days of delivery. Items must be in "as-new" condition in original packaging.  

  • One-Year Warranty: Covers manufacturing defects. Does not cover accidental damage (cracked Quartz Glass), environmental abuse, or battery neglect (Deep Discharge).

Read more on The90 Gem 30-day Guarantee and Warranty

REGULATORY INFORMATION

This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

Reorient or relocate the receiving antenna.

Increase the separation between the equipment and receiver.

Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. Consult the dealer or an experienced radio/TV technician for help.

Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.

This device complies with RF exposure requirement.