There are many who say that blue is the Sarum color for Advent. This is completely incorrect. Advent Blue is an invention of CM Almy vestment makers in order to sell more vestments.
The oldest English liturgical color sequence is that of Lichfield, c. A.D. 1240 from the statutes of Bishop Pateshull:
Advent and Lent, black
Christmas, most precious vestments
St John, Circumcision, BVM, Virgins, St Michael, white
Epiphany, Apostles, Martyrs, St John Baptist, varied colours
St Mary Magdalene, Epiphany till Lent and Pentecost till Advent, according to the will of the sacristan
There also is this instruction appended: "All things must be modified accordin to the means of the church."
Below is a description of the Sarum color cycle from Percy Dearmer's The Parson's Handbook:
Every Sunday of the Year except in Lent
Passion & Palm Sundays
Only the Blessed Virgin (and NOT for saints who weren't martyrs)
Yellow & Green:
Advent and Lent (at a later date)
Incidentally, blue and violet were consider as pertaining to black days and were used in Requeims and eventually Lent and Advent. Blue copes can be seen in depictions of Requiems.