Sparkfun Electronics WS2812 Breakout Hookup Manual page 15

The size of the bulb can either be 8mm or 5mm. The LEDs can be diffused or clear depending on how they were
manufactured.
Diffused 8mm (5 Pack)
Diffused 5mm (5 Pack)
Clear 5mm (5 Pack)
Through-Hole LED Pinout
The datasheet for the WS2812 addressable through-hole LEDs is not clear with the pinout. For reference, you can
refer to the bulb's flat edge and the length of the terminals as indicated below.
Clear Addressable 5mm LED
Note: Just like the WS2812 breakout boards, we recommend adding a 0.1 μF capacitor between each
WS2812 LED's VDD and GND.
Diffused 8mm addressable LEDs connected on a breadboard.
Diffused Addressable 5mm LED