Names and images of some of the most famous Gemstones, Megagems and more.
The United States National Museum was founded in 1846 as part of the Smithsonian Institution.
Smithsonian Museum.
Megagems.
In the USA, the Smithsonian Institutions National Gem Collection Contains some of the Largest, Finest and most Beautiful Gemstones Ever Found. The Megagems are Housed at the National Museum of Natural History in Washington, DC.
The two large stones in the picture above are two of the largest high-quality topaz crystals ever found, also from Brazil.
The American Golden Topaz. 
At 22,892.5 Carats, the 4.6kg (10.1lb) topaz was cut from a Brazilian cobble in the late 1980s.
The term MEGAGEM although not an official one, nonetheless represents a group of gemstones that stand out from others of their type in size and beauty. Many gems in the Smithsonian’s National Gem Collection take their name’s from people who donated them to the collection.
Peridot 
This 311.8- carat Peridot from Zabargad, Egypt, is one of the largest Peridot gems known. Peridot is the gem-variety of mineral forsterite. The green colouring is caused by iron, the more iron, the deeper the colour.
Heliodor.
The Common name for Heliodor is golden Beryl. On of the world’s largest cut beryl Stones 2,054 carat flawless golden colour Beryl.
Grossular Garnet.
Just one of the 15 minerals known as Garnet, Grossular may be pink, orange, red orange, yellow, brown, or green.
Tanzanite
Tanzanite weights 122,7 carats, Tanzanite is pleochroic, which means that it shows different colours depending on the viewing angle.
Blue Heart Diamond.
Paris cut this heart shape, which weighs 30.82 metric carats and is of a rare deep blue color, sometime between 1909 and 1910.
Most Famous Diamonds.
Three of the world’s most famous blue diamonds. Left to right: The Heart of Eternity,
the Hope, and the Blue Heart Diamond; 27, 45 and 30 carats, respectively. The Hope
looks larger than 45 carats because it is a rather flat stone. The Heart of Eternity
is Fancy Vivid Blue, the Hope is Fancy Deep Grayish-Blue and the Blue Heart’s color
grade is still unknown. (Probably Fancy Vivid or Fancy Deep.)
Maharani Cat’s Eye
Found in Sir Lanka, The Maharani Cat’s Eye is a variety of cheysberyl and is named after the bright, vertical band of many specimens, caused by light reflecting off titanium oxide crystals. The 58.19 carat honey coloured chrysoberyl cat’s eye discovered in Sri Lanka is one of the finest gems of its kind. It is currently displayed in the Smithsonian National Museum of Natural History in Washington, D.C.
Quartz Sphere
Fashioned in China in 1923-24 from a crystal probably found in Burma, this is the worlds largest hnown, flawless quarts sphere. It is 33cm (13″) in diameter.
Hope you enjoyed this story about Mega Gemstones.
Leave me a comment, help me find more.
Wendy.