Title: His Forgotten Wife
Description: The boss secretly wed her…  then forgot!  Ares Demetrius wakes from a coma to find his family scheming to steal his company. The first call the billionaire makes is to loyal assistant Dolly Singh—to demand she become his fake fiancée to protect his business empire. Except his accident has made him forget…they’re already married!  Unlike Ares, Dolly remembers every excruciating their clandestine wedding and her mortifying love confession. To refuse his proposal would be to relive that. This time, though, Dolly is playing with fire by accepting Ares’s diamond. Because the attraction isn’t just scorching—it’s mutual… 

No mention of a diamond in the book. 
Personally,  this was a great read, esp with his quirks?, no miraculous cure, just logical solutions. This is a standalone book, these other characters, would make good sequels
Christina - coworker and long time friend
Isaih King, psychologist and long time friend,
People: Ares Demetrius, Dolly Singh