Thailand has been known for a long decade as the world center in production and trading colored stones and also the most important market of gem corundums, particularly Ruby and Blue Sapphire – the most famous colored stones around the world. It has possessed high-level skill in gem cutting as well as enhancing the quality of colored stones with heat from the so-called “Heat Treatment of Gemstones” – the great wisdom of Thai gem and jewelry industry. Thailand’s cut stones have attained widespread acceptance for international standard quality and are in high demand in the world market. Various colored stones from Thailand are exported to overseas with the value of nearly one thousand million US dollars a year. Today, Thailand becomes the world’s largest manufacturer and exporter of Ruby and Sapphire.
Ruby derives from the Latin “ruber”, through the original form “rubinus”, which means “red”. The beauty, rarity and historical mystique of ruby are undeniable. Ruby is July’s birthstone, the gemstone for Capricorns and the traditional 15th and 40th anniversary gift.
Ruby is the most valuable variety of the gem species corundum. Ruby can command the highest per carat price of any colored stone. The most valuable ruby colors are red to slightly purplish red with medium to medium dark tones and intense saturation. All corundum varieties are made of aluminum oxide, a mixture of aluminum and oxygen. The specific conditions under which corundum forms have a strong effect on its color and appearance. The trace element chromium causes ruby to be red, and can also cause fluorescence, which intensifies body color. Blood is another symbol of ruby’s color. Descriptions have compared ruby to the pigeon’s blood described color of ruby which is vivid red with soft, glowing, red fluorescence. Fine quality rubies over one carat are rare, but commercial quality rubies are commonly available in size from melee and up. As ruby is one of the toughest gemstones and with no cleavage, breakage rarely occurs. This combined with the fact that ruby comes in many different colors and sizes, makes them perfect for all types of jewelry.
The name “sapphire” is believed to be derived from the Greek “sappheiros”, a word for blue. According to oriental belief, sapphire is the gem of Saturn. Blue sapphire is also September’s birthstone, the gemstone for Taurus and the traditional 5th and 45th anniversary gift.
The term sapphire alone describes the blue variety of gem corundum. Other colors have a color prefix such as yellow sapphire, green sapphire, pink sapphire and orange sapphire, which all of them are called Fancy Sapphire. When trace elements are iron and titanium, the corundum is blue sapphire. Only a few hundredths of percent of iron and titanium can cause the color, and the more iron the corundum contains, the darker the blue will be. The term ruby is reserved for corundums of a red color. In Asia, pink corundums are also considered rubies. Outside Asia, such gems are generally termed pink sapphires.
Blue Sapphire is one of the world’s most expensive gems, especially in the United States. Its price is equivalent to those of fine ruby or emerald. Blue Sapphire excels in hardness 9. Its resistance to scratching and other damages makes it ideal for setting in jewelry that is worn everyday. Royal Blue is one of the descriptions of blue sapphire’s color. It describes vivid blue with intense blue color.
The most highly valued sapphires are blue to violetish blue, in medium to medium dark tones. Preferred sapphires also have strong to vivid saturation. The saturation should be as strong as possible without darkening the tone and compromising brilliance. Some top-quality, large blue sapphires are extremely rare and command exceptionally high prices, but commercial quality sapphires are commonly available in size from melee and up. Blue sapphire sales have increased with the growing demand for platinum, partly because the gem complements the cool toned metal so well.
Source : Thai Gem and Jewelry Information Center The Gem and Jewelry Institute of Thailand (Public Organization) 2015