How does Dorothea justify wearing the emeralds?

Dorothea's religious persuasion makes her generally feel that the wearing of jewelry reflects a sinful nature and that jewels should not be worn in company. When she opens the box and finds the emeralds, however, she becomes suffused with a "new current of feeling." In order to justify to herself her pleasure at seeing the emeralds, she alludes to the Revelation of St. John, in which gems are used as "spiritual emblems." She describes the jewels as being akin to "fragments of heaven." In this way, she is able to see the emeralds as an outward reflection of her Christian faith, rather than as an affront to it, as they might otherwise have been seen. Because she is not enjoying the beauty of the jewels purely for their own sake—now, she decides they represent something greater—she feels that she can justify keeping them.
Celia is rather shocked by this and evidently not completely convinced by the explanation—she asks in some disbelief if Dorothea intends to wear the jewels in public, not understanding Dorothea's feelings of "mystic joy" on the subject.