Ελληνικά 
English Blue Sapphire
Sapphire is a corundum, a sister stone to ruby, one of the four gemological gemstones, along with ruby, emerald and diamond. The name comes from the Semitic word zafir which means blue stone, which passed in Greece of Hellenistic times, as sapphire, always with the same meaning. Today we know that corundum, called sapphire, exists in all colors and that ruby belongs to the same family. of corundum (aluminum oxide). The blue color is obtained from alloys of titanium and iron. Sapphire is a very hard mineral (9 on the Mohs scale), the third hardest mineral after Diamond and Ruby. Primary component of explosive rocks, found in shale or metamorphic rock.
The sapphires of Southeast Asia were created by the collision of the Indian continent with the Asian continent. The tectonic movement has led to large-scale displacements on the earth's surface, resulting in the formation of minerals and the creation of areas called orthogonal zones. Many of the mines and sapphires are located in these zones.
Pan-African orogeny occurred 750 to 450 million years ago, resulting in the creation of gemstone reserves in Kenya, Tanzania, Mozambique, Madagascar, Sri Lanka and southern India. The conflict between the Indian subcontinent and the Asian continent occurred "just" 45 to 5 million years ago. This created the sapphires of Pakistan, northern India, Nepal, Myanmar, Thailand and China.
The largest sapphire deposits are found today in Sri Lanka, Queensland, Australia, South Africa, India, Madagascar, Thailand and North Carolina in the USA.
Some blue sapphires have rutile fibers trapped in small multi-layered cavities and create six-ray asteroid iridescence. They are called Star sapphire stars, but are usually less valuable than other sapphires. The largest star sapphire is The Star of Adam weighing 1404.49 carats mined in Ratnapura, Sri Lanka Blue Belle, a blue sapphire weighing 392.52 carats, is the most expensive sapphire in history. Sold in November 2014 by Christie's $ 17.564.156,00 dethroning the famous Richelieu, blue sapphires from Kashmir.