The Mystery of the Nourdon Blue by Amanda Brenner
Series: Sid Langdon Mysteries, Book 3.
Approx. 65,040 words.
Published on July 12, 2011.
Two men are obsessed with a legendary jewel that vanished during the Crimean War. Now one of them is missing, and Sid Langdon has been hired to find him. When the trail goes cold, Sid decides to trace the stone instead, and uncovers a murky world of murderous intrigue along the trail to the Nourdon Blue.