The book really should have been called: Opals: A book about a girl named Opal who finds adventure and romance and oh yes, opals. Yes, opals were the driving force of this book.
The plot was slightly campy: Jessica (who you find out is actually named Opal) feels unloved by her family--and for good reason, as you'll find out. She befriends an old opal miner, Ben, who convinces her to marry his son. She ends up in an arranged marriage with his son Joss (the peacock; yes, he's a bit arrogant), due to certain inheritence requirements that Ben sets up. They has a love/hate relationship. He's also an opal mine owner and the couple move to Australia where Joss runs his company. Jessica finds mystery, adventure and love in the "wild land."
I enjoyed reading it. The book was fun, educational (seriously, you learn a lot about opals) and had a nice twisty mystery. It had nice gothic elements but it's never scary. I wouldn't have minded more romance, but oh well, it was still a good book.
On another note, I just reread Silent in the Grave and it was just as good as I remember! I think I'd even rate it a 9.5. I can't wait until the third book in the series is published.