"Robed all in glimmering white, like clouds about the moon; she herself seemed to shine with a soft light. On her finger was Nenya, the ring wrought of Mithril."
There are no words that closely correspond to those words in Sindarin (IMHO), except maybe bronwe, 'faith' -- however, it also means 'endurance' and 'lasting quality', so it might not be what you're looking for...