I often use them with Master Writs on some of the rarer styles that I either don't have any or have very few, I've gone through over 2 dozen of them this way.
I usually use them as a way to get rare materials. I don't really do master writs, but I make a lot of furnishings that use Dwemer Frame/Culanda Lacquer/Ivory Brigade clasps, which can be expensive. I use the stones to craft gear in whatever style I need, then immediately decon it. I usually get the mat when I do so.