Gideon, Hilary and Opal are my top names (I prefer the Hilary spelling)
Your girls name list is very different to your boys. Apart from Hillary and Mirabel, the rest are pretty standard middle class on the way up names which was surprising. Opal is more on the same lines as the boys.
How about Jewel itself? Sapphire or Sapphira, more unusual flowers like Dahlia or Delphine. Darrell for a girl or Celie, Zena, Shoshana or Aster, Rumer is maybe along the same lines.
For boys maybe Bede, Wilbur, Ari, Akira, Solomon, Naaman or Abraham (Abe)