Stone 588 — Gerald A. Browne

An octahedral crystal that came into the hands of diamond merchant Phillip Springer's father many years earlier, Stone 588 lay ignored because it was so obviously flawed: a rough, whitish-opaque lump with a chipped corner, clearly of no commercial value.
But Springer slowly becomes aware of its special qualities. It is Audrey, the woman he loves, who begins to shake his scepticism. Audrey is wealthy, beautiful, sensuous, smart, practical and, unlike Springer, psychically adventurous. She believes that the stone has healing powers. She uses her elderly Aunt Libby - a woman of vast riches and vast (but subtly-wielded) power - to prove it.
Libby, sharp and greedy, recognises the true value of the stone. So do others. But by the time a hundred-million-dollar bribe and a successful theft reveal that value to Springer, it is too late. His young son, Jake is critically ill - and Springer must embark on a desperate chase that turns ruthless and bloody, leading to an ingenious burglary in the vaults of Fifth Avenue's most opulent jeweller, a harrowing murder in the Trump Tower and a climactic breakneck chase across the spires of St Patrick's Cathedral.