The ability to make cards magically and mysteriously change from one color to another requires some sleight of hand and a good story to dress up what could appear too obvious or boring. The sleight of hand is used in many beginners card tricks and can be learnt quickly and applied to many different tricks. The routine can be modified and is only limited by your imagination. Finding unique ways to make the trick look more difficult or more spectacular is what magic is all about.
I had a request for this one so here’s a simple easy handling of this effect. There are literally dozens of ways this effect can be achieved but this is a good beginner method. – magicalmaniac77