When blue has to be deep and clear, it's got to be London Blue Topaz.

This has been cut with the checkerboard cut (my favorite cut). 

Here we have it in an Emerald cut measuring 12x10mm and weighing 7 carats. The center stone is accented with two 5 pt. CZ's on either side.  It's a good, solid ring.

This setting has a strong structure and is well built. Look at the thickness of the metal in the prongs and the ring shank