Change ParticleSystem colour one particle at a time - or by location

Hey.

EDIT: I also want to change particle colour on distance from world centre, and just tried plugging (particle info: location) output into separate xyz and on into (colour mix) but the particles are not changing colour. Any simple node setup that works?

I have a field of particles and I want to change its colour from Blue to Red by random individual particles changing colour.

I could do that by beginning to introduce new particles in that colour as old die out but it would mean I need to precisely set up particle generation to match older field dying out, and this does not account for particle death rate - What if I want to change colour of 10 individual particles within a single lifetime?