The best color for cs is clear. If you are getting yellow colored cs it means the silver particles have aglomerated (come together to form larger particles, not good). It is still usable but not what I would use (maybe use for my pets or plants). What generator are you using? If it is a Silvergen or Silverpuppy your cs should be clear. If it is a home made unit or a plain non-current contolled unit your results will vary more and you have more of a chance ending up with a yellow or darker cs product. Use good quality distilled water, keep an eye on the the generator as it produces the cs. If you notice any change in color stop the process. The clear cs is what you want.