You got that right! See here: http://www.etymonline.com/index.php?term=cosmos&allowed_in_frame=0 (This is one of my favorite sites.)
Thank you much for this site. I love googling ethimology of Greek words, and this site seems to be one of the best or just the best
I can only imagine it's the "s" in κοσμήματα. It's just an "s" that sounds heavier before the "μ". Try it. You'll see that : koS mi mata is not as fluid/smooth as koZ mi mata.