cut the end of the spring that has the same coil diameter into the next coil..
if the coils are tapered DO NOT CUT THEM, you will have seating problems.
i line up the end of the spring with the next coil. so you cut off a full ring.
i do this at a slow speed with a cut off wheel and slowly to not build up heat.
A hint to help avoid heating up the spring is soak a rag in cold water, and while your cutting stop several times and wipe the metal with the cold rag until it feels cold again. this will help dissipate the heat instead of having all of it build up.