Saturday, 17 August 2013

Large Gemstones

Found in 1967 at Vega de San Juan mine in Colombia, the Gachala Emerald is an uncut emerald crystal weighing 858 carats. It was donated to the Smithsonian Institution by New York jeweler Harry Winston.
The largest pearl ever found is known variously as the ‘Pearl of Lao Tzu’ or ‘The Pearl of Allah’. It measures 9.45 inches in diameter and weighs 14.1 pounds (6.4 kilograms) or around 31,893.5 carats.

It was extracted from a giant clam off the coast of Palawan Island, Philippines on May 7, 1934, and given to American Wilburn Cobb as a token of gratitude for his having saved the life of the Palawan village chief’s son.
The Olympic Australis Opal is the largest opal yet found. It was found in 1956 in the outback opal gemstone mining town of Coober Pedy in South Australia.

It consists of 99% gem opal and weighs 17,000 carats (3450 grams).
The Black Star of Queensland is a 733-carat (147 g) black sapphire, and the world's largest gem quality star sapphire. It was discovered in Australia in the 1930s.
The Samarian Spinel is a 500-carat (100 g) spinel gemstone that is the largest of its kind in the world. It is part of the Iranian Crown Jewels.

The Samarian Spinel has a hole in it. According to a diary entry of the court physician to the Iranian Shah Nasser al-Din Shah Qajar, the King told the physician that the stone once adorned the neck of the biblical golden calf, which the Israelites are said to have made while Moses was receiving the Ten Commandments. A diamond was added later to conceal the hole.
The Star of Bombay is a 182-carat (36.4-g) cabochon-cut star sapphire originating from Sri Lanka. The violet-blue gem was given to silent film actress Mary Pickford by her husband, Douglas Fairbanks.

She bequeathed it to the Smithsonian Institution. It is the namesake of Bombay Sapphire, a British gin.
Alexandrite is renowned for its color change from red under incandescent light, to green in daylight or fluorescent light. The Smithsonian museums' Alexandrite is a 65.08 carat square-cushion cut alexandrite from Sri Lanka and is the largest known.