The Diamond of Hishep-Ratep

From the introduction: What sages know: prince Hishep-Ratep was fearsome and wealthy, but he perished regardless on a campaign in a distant land, as foretold by the six prophets. As a follower of demon-god Ahriman, Hishep-Ratep was buried where he fell. With him was buried his legendary lifestone, a large diamond.