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

This has been cut with the checkerboard cut (my favorite cut for ovals).  Add to that the small accent stone on top an you have quite a tasteful pendant.

Set in a simple, oval .925 Sterling Silver basket (nice and heavy) that lets the London Blue Topaz do it's thing, and is accented with a nice, well cut CZ.  We use a special alloy in our sterling silver that is tarnish resistant, so your pendant will be beautiful AND hassle-free for a long time to come.

The stone weighs a healthy 7 carats, and the mounting is what you'd expect to find holding such a nice stone.