Then at last there came a day when the Duke sent for him and in the presence of all his lords told them the story and passed the crown and the dagger and the jewel from hand to hand; and the lords eyed the stone curiously and handled it tenderly; and then the Duke said that the knight who could, for the sake of honour, restore a jewel that could buy a county—there was not the like of it in the world, save in the Emperor's crown—was a true knight indeed; and therefore he made Robert Lord of the Marches, put the crown on his head, and a purple robe with a cape of miniver on his shoulders, and commanded that he should be used by all as if of royal birth.
The greatness of his reward was a surprise to Robert, and he had it in his heart to tell the Duke the truth. But the lords passed before him and did obeisance, and he put the good hour aside.
Very soon Robert set out for the Castle of the Marches; and he found it a marvellous house, fit for a king, with wide lands. And there he abode for several years, and did worthily; for he was an excellent knight, and a prudent general; moreover he was just and kind; and the people feared and obeyed his rule, and lived in peace, though none loved Robert; but he made the land prosperous and great, and cleared it of robbers, and raised a mighty revenue for the Duke, who praised him and made him great presents.
One day he heard that the Duke was ill; the next a courier came in haste to summon him to the Duke's presence; he wondered at this; but went with a great retinue. He found the Duke feeble and bent, but with a bright eye; he kissed Robert, like a brother prince, and as they sate alone he opened his heart to him and told him that he had done worthily; he had none of his kin, or none fit to hold his dukedom after him; but that all he desired was that his people should be well ruled, and that he had determined that Robert should succeed him. "There will be envious and grasping hands," he said, "held out—but you are strong and wise, and the people will be content to be ruled by you," and then he showed him a paper that made him a prince in title, and that gave him the Dukedom on his own death.
Now there lived in the Duke's house a wise and learned man named Paul, an alchemist, who knew the courses of the stars and the virtues of plants, and many other secret things; and the Duke delighted much in his conversation, which was ingenious and learned. But Robert heard him vacantly, thinking that such studies were fit only for children. And Paul being old and gentle, loved not Robert, but held that the Duke trusted him overmuch. And one night, when Robert and other lords were sitting with the Duke, Paul being present, the talk turned on the virtues of gems; and Paul, as if making an effort that he had long prepared for, told the Duke of a curious liquor, an aqua fortis, that he had distilled, which was a marvellous thing to test the worth of gems, and would tell the true from the false; and the Duke bade him bring the liquor and show him how the spirit worked. And it seemed to Robert that, as Paul spoke, a shadowy hand came from the darkness and clutched at his heart, enveloping him in blackness, so that he sate in a cold dream. And Paul went out, and presently returned bringing a small phial of gold—for the liquor, he said, would eat its way through any baser metal—and in the other hand a little dish of gems. Some of them, he said, were true gems, others of them less precious, and others naught but sparkling glass; and he poured a drop on each; the true gems sparkled unhurt in the clear liquid, the less precious threw off little flakes of impurity, and the glass hissed and melted in the potent venom. And Robert, contrary to his wont, came and stood, sick at heart, feeling the old man's eyes fixed on him with a steady gaze. At last Paul said, "The Prince Robert"—for the Duke had told the lords of the honour he had given him—"seems to wonder more than his wont at these simple toys and tricks; shall not the Duke let us test the great ruby, that its worth may be the better proven? perhaps too it has some small impurity to be purged away, and will shine more bravely, like a noble heart under affliction." And the Duke said, "Yes, let the ruby be brought."
So the lord that had the charge of the Duke's jewels brought a casket, and there in its place lay the great ruby, red as blood. And Robert would have spoken, but the words died upon his tongue, and he saw the shadow of the end.
Then Paul took the ruby and laid it on his dish; and as he raised the phial to pour, he looked at Robert, and said "But perhaps it is shame to treat so great a gem so discourteously?" And the Duke being old and curious said, "Nay, but pour." But then, as Paul raised the phial, the Duke lifted his hand, and said very pleasantly, "Yet after all, I hold not the jewel my own, but the Lord Robert's, who hath so faithfully restored it to me. What will you, my lord?" he said, turning with a smile to Robert. And Robert, looking and smiling very stonily, said, in a voice that he could scarcely command, "Pour, sir, pour!" So Paul poured the liquor.