The Sapphire Sea — John B. Robinson

Plagued by a bitter divorce and an over-bearing father, Lonny Cushman has fled his old life trading high-quality gems and attending society balls in New York City to scout the lawless sapphire fields of northern Madagascar. Homesick and lonely, he dreams of finding the perfect stone that will allow him to establish an independent career on West 47th Street and renew his relationship with his seven-year-old daughter. But when he finally unearths the greatest sapphire discovered in the last hundred years, the power brokers of Diego Suarez just want him dead ...