The color of a pretty, finished weld is nice, but people worry way too much on the color. Of course a dark grey (rough looking) weld usually is indicative of a problem, some blue color isn't going to hurt the weld at all. Any color on a weld is only surface CONTAMINATION. Many times, stainless will rust if you don't clean this contamination off.

all the welds I saw in this thread look just fine to me, even the darkest ones.