I have a "rough" edge in front of my sink on quartz countertop; how can I smooth it out? It has ruined a number of my shirts where they hit the edge of the countertop.

There are a few ways to grind the surface, but I would recommend you get a local fabricator or installer to take a look at it. If you take too much material off it will affect the look of the counter and its an expensive replacement vs getting someone who is a professional to do the job.

got any pictures?

It looks perfectly "normal"; but when you run your hand over it, it feels rough. It took me several years to figure out what was happening to my shirts!

It can be re-polished by a fabricator. There's nothing you can do without diamond polishing pads, and by the time you buy those, you might as well pay someone to do it. I'd call whoever installed it.