A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum. Other varieties of gem-quality corundum are called sapphires, Ruby is one of the traditional cardinal gems, together with amethyst, sapphire and diamond. They word ruby comes from ruber, Latin for red, the color of a ruby is due to the element chromium. The quality of a ruby is determined by its color and clarity, the brightest and most valuable red called blood-red or pigeon blood, commands a large premium over other rubies of similar quality. After color follows clarity, similar to diamonds, a stone will command a premium. Ruby is the birthstone for July and is usually more pink than garnet. The worlds most expensive ruby is the Sunrise Ruby, rubies have a hardness of 9.0 on the Mohs scale of mineral hardness. Among the natural gems only moissanite and diamond are harder, with diamond having a Mohs hardness of 10.0, when a chromium atom replaces an occasional aluminum atom, it too loses 3 electrons to become a chromium3+ ion to maintain the charge balance of the Al2O3 crystal.
However, the Cr3+ ions are larger and have electron orbitals in different directions than aluminum, the octahedral arrangement of the O2− ions is distorted, and the energy levels of the different orbitals of those Cr3+ ions are slightly altered because of the directions to the O2− ions. Those energy differences correspond to absorption in the ultraviolet, violet, if one percent of the aluminum ions are replaced by chromium in ruby, the yellow-green absorption results in a red color for the gem. Additionally, absorption at any of the above wavelengths stimulates fluorescent emission of 694-nanometer-wavelength red light, after absorbing short-wavelength light, there is short interval of time when the crystal lattice of ruby is in an excited state before fluorescence occurs. If 694-nanometer photons pass through the crystal during that time, they can stimulate more fluorescent photons to be emitted in-phase with them, thus strengthening the intensity of that red light. By arranging mirrors or other means to pass emitted light repeatedly through the crystal, all natural rubies have imperfections in them, including color impurities and inclusions of rutile needles known as silk.
Gemologists use these needle inclusions found in natural rubies to distinguish them from synthetics, usually, the rough stone is heated before cutting. These days, almost all rubies are treated in some form, untreated rubies of high quality command a large premium. Some rubies show a three-point or six-point asterism or star and these rubies are cut into cabochons to display the effect properly. Asterisms are best visible with a source and move across the stone as the light moves or the stone is rotated. Such effects occur when light is reflected off the silk in a certain way and this is one example where inclusions increase the value of a gemstone
Dodoma Region is one of Tanzanias 30 administrative regions. The regional capital is the city of Dodoma, according to the 2012 national census, the region had a population of 2,083,588, which was lower than the pre-census projection of 2,214,657. For 2002-2012, the regions 2.1 percent average annual growth rate was the twentieth highest in the country. It was the seventeenth most densely populated region with 50 people per square kilometer, the main tribes of the region are the Gogo, the Warangi, and the Wasandawi, Dodoma means sunk in the Gogo language. The city of Dodoma, the largest city and capital of the region, originally began as a small Gogo village in the early 19th century, the city was formally established in 1907 by German colonists during construction of the Tanzanian central railway. The region has a history of famine and economic difficulties. Along with Kondoa and Singida it was hard by the famine of the 1910s. One report by a British officer in Dodoma in December 1916 reported that The whole District has been ransacked for cattle, the Germans had killed 26,000 animals, and the British 5,659.
The problems continued throughout 1917, and in November 1917 drought turned it into a crisis, some 30,000, about 1 in 5 of the population of the district at the time died. Thousands of people emigrated, and others sold starving cattle for just a shilling at the market in Dodoma, smallpox was prevalent, and a Spanish influenza epidemic killed an estimated 50, 000–80,000 in Tanganyika between 1918 and 1920. When the British took over the country, they favoured Dar es Salaam and Arusha, the importance declined further in the 1960s when the Tanzam Highway was built by the Chinese, connecting Dar es Salaam to Morogoro and Iringa. On 9 December 1961, Tanganyika won independence from Britain, in 1963, the provinces of the new nation were divided into smaller administrative units and were renamed regions, and the Dodoma Region was established. However, in 1973, the Tanzanian government announced that the capital would be moved from Dar es Salaam to a central location to better serve the needs of the people.
Dodoma was selected for this purpose, as it was an established town at a major crossroads with an agreeable climate. The Dodoma Region lies in the heart of Tanzania in the part of the country. The region, which is primarily semi-arid, covers an area of 41,311 square kilometres, the region is bordered by the Manyara Region to the north, the Singida Region to the west, the Iringa Region to the south, and the Morogoro Region to the southeast. The region produces beans, grain, coffee, cattle are raised and marketed. The region is divided into seven districts, Dodoma is the centre of educational activity in the region
Tanzania /ˌtænzəˈniːə/, officially the United Republic of Tanzania, is a country in Eastern Africa within the African Great Lakes region. Parts of the country are in Southern Africa, Mount Kilimanjaro, Africas highest mountain, is in northeastern Tanzania. Tanzanias population of 51.82 million is diverse, composed of ethnic, linguistic. Dar es Salaam, the capital, retains most government offices and is the countrys largest city, principal port. Tanzania is a one party dominant state with the Chama Cha Mapinduzi party in power, from its formation until 1992, it was the only legally permitted party in the country. Elections for president and all National Assembly seats were last held in October 2015, the CCM holds approximately 75% of the seats in the assembly. Prehistoric population migrations include Southern Cushitic speakers, who are ancestral to the Iraqw and Burunge and who moved south from Ethiopia into Tanzania. Based on linguistic evidence, there may have two movements into Tanzania of Eastern Cushitic people at about 4,000 and 2,000 years ago.
These movements took place at about the time as the settlement of the iron-making Mashariki Bantu from West Africa in the Lake Victoria. They brought with them the west African planting tradition and the staple of yams. They subsequently migrated out of these regions across the rest of Tanzania, European colonialism began in mainland Tanzania during the late 19th century when Germany formed German East Africa, which gave way to British rule following World War I. The mainland was governed as Tanganyika, with the Zanzibar Archipelago remaining a separate colonial jurisdiction, following their respective independence in 1961 and 1963, the two entities merged in April 1964 to form the United Republic of Tanzania. Tanzania is mountainous and densely forested in the northeast, where Mount Kilimanjaro is located, three of Africas Great Lakes are partly within Tanzania. To the north and west lie Lake Victoria, Africas largest lake, and Lake Tanganyika, the eastern shore is hot and humid, with the Zanzibar Archipelago just offshore.
The Menai Bay Conservation Area is Zanzibars largest marine protected area, over 100 different languages are spoken in Tanzania, making it the most linguistically diverse country in East Africa. Among the languages spoken in Tanzania are all four of Africas language families, Cushitic, Nilotic and English are Tanzanias official languages. In connection with his Ujamaa social policies, President Nyerere encouraged the use of Swahili, approximately 10% of Tanzanians speak Swahili as a first language, and up to 90% speak it as a second language. Most Tanzanians thus speak both Swahili and a language, many educated Tanzanians are trilingual, speaking English