Concerning Queen Paola's taste for jewels, I remember reading in a PdV article many years ago on this subjet. They said that she does not really like coloured precious stones (meaning emeralds, rubies, etc.), but she prefers diamonds and pearls, and this seems obvious, considering the number of pear necklaces she owns. On the contrary, she only owns a diamond floral brooch with a ruby, a pair of diamonds and aquamarine earrings and a brooch with and emerald encircled by diamonds (often worn by Grand Duchess Josephine Charlotte of Luxemburg).
Here are some photos of above mentioned jewels: Ruby brooch
Aquamarines, during the state visit to Austria:
Emeralds (the emeralds beads necklace is probably a loan from a jeweller):