Stone 588 - Gerald A. Browne

 

Author of 11 Harrowhouse. He wrote gem-themed heist thrillers. Good books. This one is about a mysterious crystal found by a diamond dealer. Stone 588. No gem experts know what it is. From 1986.

https://en.wikipedia.org/wiki/Gerald_A._Browne

https://www.publishersweekly.com/978-0-87795-539-9