Hi there!
The "Tarnished Silver Metallic" on my wife's '07 Malibu (which may not be the Solstice silver, but it's close) is a royal ***** to spray. It's almost impossible to match.
GM released the "prime" color, which is the regular color (not to be confused with primer). They also have "variants" which are subtle changes in the color or metallic size/density. If you're going to repaint a panel, you must use the "variant card deck" to figure out which variant of the color you've got. The paint number is insufficient unless you're repainting the whole car (in which case you just use the "prime" color).
I assume (!) that the prime/variant mess is because GM can't guarantee that all of the cars that color are going to end up the same, so they push the problem off to the body shop.
The only way you'll ever get a color match on this color is a whole-car repaint by a good painter (which leaves GM out).
Well I just had my car repainted (almost the entire car) and today we realized that the rear quarter now looks white in certain light. It's bizarre because now the doors match but the rear quarter doesn't. If I hadn't seen them sanding it down myself I would have thought they skipped that part.