The back of the book description of Tourmaline by Joanna Scott says it's about an American family traveling to an island off the coast of Italy hoping to make a fortune in gemstones. I suppose that story is in there somewhere but I never found it.
The problem is, the book is written as a breezy conversation or perhaps a monolog. The protagonist rambles on about Elba, the trip, bits and pieces of history and various people met at different times. I kept hoping things would settle down but it never seemed to. The book from start to finish just rambled on with calls to remember this or remember that.