Mohammed Shah, a feeble irresolute man, was appointed by Fate to hold the sceptre of India at the moment when she was to meet her fiercest foe. Thamas Kouli Khan, better known as Nadir Shah, had raised himself to the throne of Persia and, like all usurpers, felt the need of strengthening himself at home by a successful foreign war. He accordingly invaded India, at the head of a small force of hardy fighters, who, in the words of Nadir's grandiloquent Persian biographer, "threw the shadow of their sabers across the existence of their foes." In short they killed all before them and entered the Punjaub early in the year 1739, by pretty much the same route as that followed by Baber, the ancestors of the Moguls. But the Moguls were changed since the days of Baber. Mohammed Shah was completely defeated the moment he encountered Nadir Shah.

However, booty, rather than territory, was the object of the invader, so he did not dethrone Mohammed, but only levied tribute from him. The defeated Mogul gave an unheard-of quantity of jewels to Nadir Shah "who was at first reluctant to receive them, but at length consented to place the seal of his acceptance upon the mirror of his request." Such reluctance is very foreign to the generally rapacious and grasping character of Nadir Shah, and probably existed only in the flowery imagination of the writer of his life.

Having become aware that the Koh-i-nûr was not among the treasures he had already sealed with his acceptance, Nadir Shah set about hunting for it, and at last a traitor was found who betrayed the secret of its hiding-place. A woman from the harem told the Persian king that the coveted diamond lay hidden in the folds of Mohammed's turban, which he never took off. Nadir accordingly one day invited his helpless friend, Mohammed, to exchange turbans with him in sign of their everlasting friendship. As in the time of the first free-will offering to Baber two centuries before, the Koh-i-nûr was once again to pass from the conquered to the conqueror, from the weak to the strong.

It is said that Nadir Shah, overjoyed at the beauty of the gem he had thus cleverly filched from his ally, called it "Koh-i-nûr" (i.e. the Rock of Light) the first time that he laid eyes upon it. If this is really a fact it is very singular. It is indeed strange that Jehangir, who was so fond of descriptive names compounded with Light, should have left it to the enemy of his race to endow one of his favorite diamonds with this poetical title. One would prefer to think that he had called his diamond the Rock of Light just as he had called his wife the Light of the World.

Upon the retreat of the conqueror the diamond was carried off with other booty. The Koh-i-nûr therefore went from Delhi into Persia, and eventually it descended to Shah Rokh, the hapless son of the mighty Nadir Shah. But he who would wear the great diamond in peace must himself be strong, and Shah Rokh was weak. The wretched prince was unable to hold the throne, usurped by his father, against the usurpations of his own lieutenants. In 1751 he was dethroned and his eyes put out by Aga Mohammed, who endeavored by the most frightful tortures to force him to give up his diamonds and other treasures. Shah Rokh however, in spite of all, still retained the Koh-i-nûr and his tormentor thereupon devised for him a diadem of boiling pitch and oil which was placed on his unhappy head. But even this expedient failed to make him give up his priceless gem.

A powerful neighbor, the lord of Kandahar, an old friend of his father, now came to Shah Rokh's assistance, put his tormentor to death, and once more placed the forlorn prince upon his tottering throne. In reward for this timely service, the Persian gave to his deliver the Koh-i-nûr in whose rays his sightless eyes could no longer rejoice. Shortly afterwards he died from the effects of his injuries.

The Koh-i-nûr was now in Afghanistan, the birthplace of Baber, while Baber's descendants on the throne of Delhi helplessly mourned its loss. It went from father to son safely enough for two generations in the land of the Afghans, and then its evil spell began to work once more.

In 1793, just after its rival, the Regent, had been lost and found in the midst of the French Revolution, the Koh-i-nûr passed by inheritance into the hands of Taimûr Shah, the king of Cabul. He left it along with his crown and his kingdom to Raman Shah, his eldest son. Raman had enjoyed the triple inheritance for only a few years when his brother rose in arms against him, and being successful, as most rebels are in Afghanistan, followed the old established etiquette of the Cabul royal family:—the messengers of Shah Shuja, the triumphant rebel, met their deposed sovereign on his way to the capital, and they put out his eyes by piercing the eyeballs repeatedly with a lancet.

This done, Shah Shuja sat himself down to enjoy the sweets of Asiatic power. The Koh-i-nûr was not immediately his, however, for it was some time before it came to light, and then by the merest accident. An officer, happening to scratch his finger against something that protruded from the plaster in the walls of the prison of poor blinded Shah Raman, turned to examine the cause of the wound. To his amazement he discovered it to be the corner of the great diamond, which the unlucky prisoner fancied he had securely hidden away. Shah Shuja wore the Koh-i-nûr in a bracelet during the brief splendor of his reign, and it was on his arm when English eyes first saw it.

Mountstuart Elphinstone, the pioneer of the weary throng of Englishmen who have trod the road to Cabul, thus speaks of the Koh-i-nûr and its possessor to whom he was accredited as ambassador in 1812: