Announcing how he had appointed Yosef over the entire Land of Egypt, Pharaoh removed the ring from his own hand and placed it on Yosef's hand, dressed him with a garment of locally valued fine linen, and placed a golden chain around his neck. This act of giving the king’s ring was a sign, that the recipient was being promoted to be second in rank to him. (Rashi Berashis 41:40)

Linen Garment

Even great Tzadikim, as long as they have not been tested, have to fear that they have not completely vested themselves from all contaminated spiritual garments. It is only through passing tests that they can completely rid themselves of these contaminated garments. When Yosef passed the test of Potifar's wife, he rid himself of these contaminated garments. This was manifested by him leaving his garment in her hand and fleeing outside. Now, having been released from jail and having completely passed this ongoing testing episode, Yosef was given a fine linen garment which manifested his complete doning of only pure spiritual garments. Later Yosef rose to a higher level of Tzadik, that is able to clean even his students and friends from contaminated garments and therefore dressed each of his brothers in fresh garments. 
(Likutay Halachos Hillchos Bitziyas Hapas 40)
 

Rabbi Dun Aryeh

http://www.zissil.com

Dun Aryeh is a writer on a number of Kabbalah / Breslov related blogs and websites.