CATALOGUE OF GEMS AND PRECIOUS STOXES. 33 



same crystal occasionally exhibiting different colors, the most ap- 

 proved tint being a "pigeon's blood" red. The sapphire, in general, 

 includes corundums of any color except the red. Specifically, the 

 name is limited in its use to the blue-colored specimens, the approved 

 tints being royal blue, velvet blue, and cornflower blue. The sap- 

 phire occasionally exhibits a different color effect by natural light 

 from that seen by artificial light, and as a rule is less brilliant by the 

 latter. 



Corundums of other colors are named according to their hues: 

 Oriental emerald, the green-colored kinds, varying in tint from a 

 lively green, exceeding that of the emerald, to a sea or blue-green. 

 Oriental amethyst, purple or amethystine. Oriental topaz, yellow, 

 rivaling the yellow diamond in brilliancy. Oriental hyacinth is 

 hyacinthine in tint and is rare. Adamantine spar includes the hair- 

 brown varieties. 



The six-rayed star seen in many clouded corundums, especially 

 when cut cabochon with the summits cutting the vertical axis of the 

 prism, is due to numerous minute crystals or layers within the stone 

 which reflect the incident light so as 'to produce the stellar effect. 

 These rays are invariably white, though the specimen may be of any 

 color, and may be best seen by artificial light. This chatoyancy, 

 when marked, gives the asteria, or star stone, also known as the star 

 ruby or star sapphire, as the case may be. Should the gem assume a 

 fibrous texture, the chatoyancy affords the "cat's-eye" ray. 



Corundum is associated with crystalline rocks as granular lime- 

 stone or dolomite, gneiss, granite, mica, and chlorite schist. The 

 finest sapphires are usually obtained from the beds of streams, either 

 in modified hexagonal prisms or in rolled masses, accompanied by 

 grains of magnetic iron ore and other heavy minerals. 



The best rubies come from the mines of upper Burma, in an area 

 about 30 miles square, of which Mogok is the center, where they are 

 found in place in crystalline limestone; they occur also in gravel and 

 in the soil of the hillsides. A similar locality exists in the marble 

 hills of Sagyin, 16 miles north of Mandalay. Ruby mines have also 

 been worked at Jagdalik, near Kabul, Afghanistan. Blue sapphires 

 are brought from Ceylon. 



The great corundum region of the United States extends from the 

 Virginia line through North and South Carolina, across Georgia and 

 into Alabama. Numerous localities are known in the crystalline 

 rocks of the region, especially in Madison, Buncombe, Haywood, 

 Jackson, Macon, and Clay Counties, North Carolina. Rubies rival- 

 ing those from Burma in color have been found in the Cowee district 

 of this State, but the region affords no commercial supply. Fine 

 gem sapphires are found on the river bars in the Upper Missouri near 

 Helena, Montana. They are most abundant at Eldorado Bar, French- 



