Mysterious color changing cameo

by Anna
(Texas)

Hi, my dad got me this cameo for Christmas a few years back. I've researched it to try to find out what material may have been used for the cameo, but haven't seen anything out there like this. It is a lavender color sometimes, but other times it appears to be a blue-green color. The setting is interesting too because the flower on the top is rose gold. Any help determining it's origin or material used would be wonderful. Thanks!!