Adafruit Industries Adafruit Industries Flora UV Index Sensor - Si1145 Light Sensor
It's small, round, and connects to the I2C bus pads. Flora can even use our library code to get calibrated light level and UV index data from the sensor. Please note: this sensor can be used by Flora but is too complex for Gemma! To use: connect the 3V, SDA and SCL, and GND pads of the sensor to your Flora 3V/SDA/SCL/GND pads, in that order. Then load up our Arduino library and example code from the classic Breakout tutorial to your Flora.
Adafruit Industries Flora UV Index Sensor - Si1145 Light Sensor
Usually ships in 1-3 business days.