I love Smoky Quartz, the soft , smooth sultry color.  Ours have been concave cut, and catches the light well.  It goes with just about anything, and won't fight with your wardrobe, complementing it instead. 

We cast our own mountings and will never use flimsy "snap tight" stuff.  A 14x10mm rectangular cut, weighing in at around 7cts, it's set in a simple basket (very solid) that lets the Smoky Quartz do it's thing. It's accented with three 5 point CZ's.