Netatmo's June bracelet is a sun sensor masquerading as a gemstone. The faceted June — showing at CES, and available for $99 in gold, gunmetal, or platinum — synchronizes with an iOS app to inform wearers of their sun exposure. The app also dishes out advice, using the sun's measured UV index to suggest its owner wears a hat, puts on sunglasses, or applies sunscreen.

Netatmo calls it a bracelet, but the June can be detached from its strap to wear as a brooch. Note that would-be sunbathers will need to keep their iOS devices close, as the sensor doesn't have its own screen. Thanks to a design by Louis Vuitton and Camille Toupet, the June successfully manages to look more like fine jewelry than something that tries to make you to wear a hat when you go outside. But even with its winning aesthetics, $99 may be a high price for a sun sensor that doesn't work on its own.