Apparently this is a German trilogy recently translated into English...I couldn't tell at all, especially as most of it was set in London.
The story raced along smoothly, with lots of action and funny dialogue. I found the time travel parts more interesting than the time spent at school. But the early school scenes obviously helped introduce the characters and established their relationships with each other.
I'm not quite sure what age group this book is aimed for.
The writing is quite light and easy to read so that any mature 11+ reader could manage it. However all the kids are in the mid teens with some light romance thrown in so that older teens could also enjoy this story.
I've also noticed a lot of (good) reviews on YA blogs, so this trilogy could be described as a great all ages read.
If you're a fan of the Ivory Tower then I think you'll love this too. It has a similar mix of mystery, historical fiction, adventure and romance.
I'm certainly looking forward to the next 2 books, Sapphire Blue and Emerald Green.
After writing the above, I spent some time checking out the covers from other countries - they have all been of a consistently high standard. But it is curious to note how they also reflect each countries opinion on what age group is reading this type of book.
The Australian cover with the younger girl featured on it, echoes my indecision about which age group this is written for.
Whereas the US cover with its sumptuous ruby gown & very mature looking young woman is definitely YA material.
However my particular favourite is the fairytale styled cover from Germany.