As a general rule I avoid artificial colors and high fructose corn syrup as much as possible (aside: have you seen the new ads by the Corn Refiners Association that claim high fructose corn syrup is just like sugar. They are clearly an impartial source of valid information, wouldn't you agree?). I decided to try my hand at homemade grenadine because everything available in stores was basically nothing more than high fructose corn syrup and artificial food coloring. I don't recall ever seeing one that included actual fruit or juice at all.
I used the recipe from Linda J. Amendt's Blue Ribbon Recipes, so I'm not going to post it here. If you want to make it check your local library, they should stock the book or something similar. And always follow safe canning procedures.
Grenadine is typically used to color and sweeten cocktails, both alcoholic and non-alcoholic. Mine did come out very red, but as you can see from the Shirley Temple pictured below, the color dilutes when added to other liquid, much more so than an artificially colored syrup would. And, even though I had to use $6 worth of pomegranates, it was still cheaper than buying a commercial version - I got about three and a half cups of syrup out of it.