Of course its randomized.
Blue and yellow stats are random... Rares (yellow) seem to get between 4-6 properties at random and they don't seem to have a level requirement (so keep them in the bank for alts)
Uniques/Sets (Gold / Green) don't have randomized stats.... They are fixed.
A well rolled rare can be better than a unique/set... Especially if you are doing some kind of specialized build.