First of all the socks are handmade.  So they will look somewhat irregular and won’t be perfect like if they were machine generated.  The socks are also very soft, as they are described as “as soft as rabbits” (line 5).  They are also made of wool, so they are probably very thick.  They are most likely a dark bluish gray with a yellow stripe, as they are described as “sea blue, shot through/by one golden thread” (line 12-13).  I say they are dark because they are described with dark imagery, such as “shark” and “blackbird” and no specific color is given.  They sound like very lovely socks.  I hope they are found!