This pair of 6.30ct  purpley blue Queensland opals (one crystal opal, one boulder opal) are hand carved into intricate sea shells and then hand carved again into one of a kind 14k rose gold earrings with pink purple and blue sapphires. 

The shell on the right is the boulder opal which you can tell by the little bit of ironstone remaining on the side of the shell. 

On the left is the wood replacement opal which is created in a slightly different manner.

 In a very simple explanation, Australian opal forms over hundreds of millions of years when silica and other minerals dissolve in water and slowly solidify. In this particular area where these opals were mined, the silica rich solution occupied space where prehistoric tree branches were buried underground and as the wood decomposed, the opal solidified in its place- leaving an opalized replica -- also called "jelly mold" fossils or pipe opal. The rough opal material then gets carved locally into these incredibly detailed sea shapes. Some opals in this collection may have encapsulated the prehistoric wood within the stone or on the back. You can think of these as the opals “thumbprint“. It is a testament to the special and unique nature in which these opals have formed.