|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 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.|
|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.|