Crystal Clear Meaning

(idiomatic) Visually clear, a sharp image, high acuity.

Example:   Reread through the manual until the instructions are crystal clear in your head.
1945, George Orwell, Animal Farm, chapter 1
  Is it not crystal clear, then, comrades, that all the evils of this life of ours spring from the tyranny of human beings?
  The picture on this TV is crystal clear – you can see every grain of sand!