The book (Handbook to Christian and Ecclesiastical Rome by Tuker and Malleson, London, 1900) where I found most of the information about seminarians' soutanes also has lots of other pieces of random Catholic trivia, much of it to do with the various religious orders with a presence in Rome. Obviously, much of what was written in 1900 is now obsolete, but interesting none the less.
Theses nuns still retained the 'Consecration' which occured 4 years after profession and was related to the ancient Christian rite of institution of deaconesses. The Catholic Encylopedia seems to confirm this.
The recipient presented herself 'in the white Carthusian habit and scapular and a white veil which is exchanged in the ceremony for a black one. She receives the gold diadem and the gold ring of the Consecrated Virgin, and the stole and the maniple of the deacon. The maniple is worn on the right arm. The rite begins with the Veni Creator, and litany of the saints, and terminates with the Te Deum. The nun chants the gospel of the Mass vested with the stole. At the daily conventual mass one of the consecrated nuns still chants the Epistle, and in the absense of a priest, she still reads the Gospel at Matins, vested with the stole.
Among Cistercian privileges is that of celebrating mass with closed doors in time of interdict, granted by Eugenius III, who was himself a Cistercian monk and a pupil of S.Bernard's.
Edited to add
Great minds... Incredibly, Fr Tucker of Dappled Things posted about the Cistercian nuns just a few hours before me.