Housekishou Richard-Shi no Nazo Kantei (Novel)

From Seven Seas: When Seigi Nakata rescued a handsome young jewelry appraiser from a group of drunken assailants, he got more than he bargained for! The appraiser is Richard Ranasinghe de Vulpian, a brilliant and mysterious British jewelry expert. Seigi hires him to appraise a family heirloom and that is just the beginning. Together, they unlock the secret messages hidden in the hearts of precious stones and those who possess them.