I have both chromium and diamond (both .5 micron), I mostly use the chromium because I find it gives a smoother edge (it might be all in my head though) both do a good job of touching up a blade, only takes about 10 passes when the edge starts to tug when shaving. I also use it to finish the blades when honing. Since you already ordered both, try them both and see which one you prefer. Hope this helps.
-dan-