Jim,
Your's is a problem that everyone who uses different platings has to face at some time. That is why I use only 24k for SlimLine kits and Ti-Gold for everything else, and hope that the labels on the bags are always correct.
It looks like you have several options.
You can sort them by color and brightness, but this doesn't work very well because there is enough variation in platings of the same kind, their age, and their appearance on the different parts to make this nothing more than a guess at best.
You can use all of the parts to assemble pens, and the difference will be obvious after they have been used for a couple months. I discovered this method when I got some bags of parts that had been mislabeled. Fortunately, most people lose the pen before they have a chance to know the difference.
A faster way to tell the difference is to buff the finish after the pen is assembled, and replace those parts whose plating came off. I tried this after the mislabeled parts got mixed in with the others.
You can throw them all away and start over. The only positive solution (unless the new parts are mislabeled).
Or, you can call whoever made the parts and ask them. I tried this, and discovered that they don't know either.