The West End Horror - Nicholas Meyer

 

Coming after The Seven-Per-Cent Solution. Sherlock Holmes. From 1976.

https://en.wikipedia.org/wiki/The_West_End_Horror

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

Green Ice, Magic, The Island, Jaws, The Deep

 

Thriller heaven? Knee deep.