Quick question: Why is the Virgin Mary's robe blue?
Madonna in Glory, by Carlo Dolci (Italy, 1616-1686), c. 1670, Oil on canvas
If you have answered "Because blue is the colour of the sky", you are wrong. That is a modern association.
The truth is (according to one of my Art History teachers), during the Renaissance, the most expensive pigment an artist could use was blue. Blue was made of crushed Lapis-Lazuli. Out of respect for "God's Mother", the people who commissioned representations of Mary wanted to give her the best and most expensive robe; the richer the commissioner, the purer the colour!
Gotta go, wouldn't want to be late for the service, now would we!
Edit: We were late and we skipped Church entirely. Darn weather! Oh well... (Thank you Mother Nature!)