There are 3 books in the Secret Diamond Sisters series.
The Secret Diamond Sisters series does not have a new book coming out soon. The latest book, Diamonds Are Forever (Book 3), was published in November 2015.
The first book in the Secret Diamond Sisters series, The Secret Diamond Sisters, was published in February 2014.
The Secret Diamond Sisters series primarily falls into the Contemporary Romance genre. This young adult series was written for ages 12-17, but can be enjoyed by adults too.