Dom Pedro, the World's Biggest Aquamarine Gem. The obelisk-shaped, blue-green gem, which was designed by famed German gem cutter Bernd Munsteiner, known as the "father of the fantasy cut," stands 14 inches (35.5 centimeters) tall and weighs 10,363 carats, or 4.6 pounds (two kilograms). (Link)
This is the most expensive pearl in the world, priced at 137.5 million dollars. It is 5 ft. high and weights 6 ton. It was unearthed in Mongolia . The pearl was formed out of fluorite mineral, it tends to glow in the dark.