How do I change the color of particles with a color ramp? I watched this tutorial https://youtu.be/eshOzshjt90 and at 2:18 he somehow magically managed to get a different color on his second particle via the color ramp. But the color ramp doesn't do anything at all? I'm really confused. How do I change or invert the color of my second particle?
If your particle system is instancing an object then you can customise the particles to sample random colours by using this node setup on your instancing object: 



Here, all I've done is use the random output of an object info node with a colour ramp :)