The world’s supply of fine rubies is drawn almost entirely from the famous ruby mines near Mogok, situated about 90 miles (145 km.) in a north-easterly direction from Mandalay in Upper Burma and at an elevation of about 4000 ft. (1200 m.) above sea-level. It is from this district that the stones of the coveted carmine-red, the so-called ‘pigeon’s blood,’ colour are obtained. The ruby occurs in a granular limestone or calcite in association with the spinel of nearly the same appearance—the ‘balas-ruby,’ oriental topaz (yellow corundum), tourmaline, and occasionally sapphire. Some stones are found in the limestone on the sides of the hills, but by far the largest quantity occur in the alluvial deposits, both gravel and clay, in the river-beds; the ruby ground is locally known as ‘_byon_.’ The stones are as a rule quite small, averaging only about four to the carat. Before the British annexation of the country in 1885 the mines were a monopoly of the Burmese sovereigns and were worked solely under royal licence. They are known to be of great antiquity, but otherwise their early history is a mystery. It is said that an astute king secured the priceless territory in 1597 from the neighbouring Chinese Shans in exchange for a small and unimportant town on the Irrawaddy; if that be so, he struck an excellent bargain. The mines were allotted to licensed miners, _twin-tsas_ (eaters of the mine) as they were called in the language of the country, who not only paid for the privilege, but were compelled to hand over to the king all stones above a certain weight. As might be anticipated this injunction caused considerable trouble, and the royal monopolists constantly suspected the miners of evading the regulation by breaking up stones of exceptional size; from subsequent experience, it is probable that large stones were in reality seldom found. Since 1887 the mines have been worked by arrangement with the Government of India by the Ruby Mines, Ltd., an English company. Its career has been far from prosperous, but during recent years, in consequence of the improved methods of working the mines and of the more generous terms afterwards accorded by the Government, greater success has been experienced; the future is, however, to some extent clouded by the advent of the synthetical stone, which has even made its way out to the East.