Emeralds

On the nature of emeralds

Emeralds are the most precious of the colored gemstones from the beryl family.  The element that is responsible for the green color is almost always chromium.  Occasionally, though, vanadium is involved. The tint can range from deep grassy greens to less verdant hues of green to slightly yellowish-greens. Some emeralds have a tinge of blue.

18K white gold ring with 1.20ct oval emerald. Available from Grimball Jewelers.

18K white gold ring with 1.20ct oval emerald. Available from Grimball Jewelers.

Depending on the quality, emeralds can range from transparent to opaque. Natural emeralds very often contain inclusions, which are sometimes referred to as "jardin" (French for garden). Inclusions are not considered faults in emeralds, although the fewer inclusions this stone has usually corresponds to a higher value. Inclusions are used as evidence that the stone is natural (not synthetic) and to identify individual stones. Oils, and, more recently, polymers are used to fill these fissures, which can enhance the beauty of the gemstone and contribute to their stability.

On the Moh's Scale of Mineral Hardness, emerald appears at an intermediate hardness of 7.5 - 8, along with other minerals such as tungsten and spinel.  However, emeralds are brittle.  All of them.  Although their color is resistant to heat and light, the stones themselves are very vulnerable to heat, pressure, and internal stress.  They are not the easiest stones to cut.

On finding emeralds and a bit of emerald mining history

Emerald deposits are found all over the world, even in North Carolina. These days Columbia is universally recognized as the largest producer of emeralds. Zambia, though far behind, is the second.

A mineral specimen containing Zambian emeralds protruding from mica. From the Smithsonian Museum of Natural History.

A mineral specimen containing Zambian emeralds protruding from mica. From the Smithsonian Museum of Natural History.

This was not always the case.

Among the earliest accounts of emerald mines are the mines located in the southern desert of Egypt near the Red Sea.  Mines that, around 50 B.C. or thereabouts, provided Queen Cleopatra with what appear to be her favored gemstone.  Though many of these ancient mines have been lost, a French adventurer and official mineralogist to the pasha of Egypt, Frédéric Cailliaud, re-discovered the emerald mine of Zubara in 1816. The remnants of Zubara as well as another mine called Sikait can still be found on Mount Smaragdus (Emerald Mountain) today.

It wasn't until 1500 years later when the Spanish conquistadors arrived in South America, searching not only for the lost city of El Dorado but also a venerated emerald as big as an ostrich egg, that the Egyptian emeralds lost prestige in favor of those from Columbia, which were larger, greener, and clearer.  In 1537 the Spanish opened their first mines along a mountain ridge north of Bogotá in an area called Chivor.  Thirty years later and about 68 miles away another mining area was cultivated called Muzo, which has revealed the finest emeralds ever found in this world.

Interesting moments in emerald history

2009. A 310 carat emerald was found in Alexander County, North Carolina.  It is considered the largest emerald found so far in North America.  To prepare it for selling it was cut down to 64.83 carats and was christened the "Carolina Emperor."

1985. The Atocha's mother lode was discovered by Mel Fisher. The Spanish treasure galleon sunk off the coast of Florida in 1622 carrying about $800 million worth of precious items such as copper, silver, gems, and, of course, emeralds. The cache of emeralds was found about 100 feet away from the mother lode and dubbed the "Emerald City."  The Emerald City has relinquished 13,500 carats of emeralds that came from the mines in Muzo, Columbia.

This 22K yellow gold and emerald cross represents the most prized of all artifacts from the Nuestra Señora de Atocha shipwreck. From The Gemological Institute of America.

This 22K yellow gold and emerald cross represents the most prized of all artifacts from the Nuestra Señora de Atocha shipwreck. From The Gemological Institute of America.

1935. An emerald was grown by a human. Although alchemists had been trying to create gemstones for thousands of years and scientists for hundreds, it was only in 1935 that Carroll Chatham discovered a way to successfully grow emeralds in a lab.  Some of his stones, including the first stone he created as well as his largest (1014 carats), are held in the Smithsonian's collections.

1805. Napoleon returned a stolen emerald to the pope. Set in what is known as the Napoleon Tiara, the emperor returned a large emerald that had been stolen from Rome by his troops in 1798.  The tiara proved to be unwearable though.  Not only was it too small to sit comfortably on a man's head but it also weighed 18 pounds.  Papal tiaras normally weighed 2 - 5 pounds.

507. Bamiyan Buddhas had emerald eyes. These gigantic monuments of Buddha were carved in the side of a sandstone cliff in Afghanistan during the early sixth century.  People of this area believed that the Buddhas's eyes were originally set with giant emeralds that flashed in the sunlight and could be seen from many miles away. Destroyed in 2001.

60. Nero used emeralds to improve his view of the gladiators. In his Natural History, Pliny mentions that Emperor Nero held an emerald up to his eye during the gladiator fights in order to view the games better.  Although beryl has been used in eyeglass lenses in the past, it is more likely that Nero's emerald filtered the sunlight rather than clarified his vision.

48 B.C. Cleopatra gave emeralds as gifts.  Perhaps because emeralds were a symbol of Egypt or perhaps because they were an emblem of power and wealth, Queen Cleopatra was known to bestow gifts of emeralds carved with her portrait upon her powerful acquaintances.

Notable emeralds

Trapiche emeralds. Trapiche emeralds are found in Columbia. The term “trapiche,” named after the Spanish word for the spoked wheel used to grind sugar cane, describes a very special growth phenomenon. Basic components usually include a six-ray star radiating from the center of the stone, a clear or dark hexagonal core at the center, and a transition between the core and the outer sectored crystal.

Trapiche emeralds. From the Smithsonian Museum of Natural History.

Trapiche emeralds. From the Smithsonian Museum of Natural History.

Mogul emerald necklace. This carved flat emerald is set in a platinum, gold, and diamond pendant necklace. The emerald was discovered in Colombia, possibly by Spanish conquistadors, and found its way to India for cutting. This emerald was most likely carved, rather than faceted, because of the natural inclusions, the shape of the original beryl crystal, or it might also have been the preferred style at the time. The floral motif carving is believed to be of the Indian Mogul style. The Mogul Empire was the imperial power that ruled most of the Indian subcontinent from the early-16th to mid-19th centuries. Often times carved gemstones were worn on the arm as amulets; threads pulled through the small drill holes on the sides of this emerald could then be tied on to the arm of the wearer. The emerald is surrounded by round diamonds and is suspended from a double row diamond necklace; the diamonds total approximately 50 carats. A hallmark indicates that the Mogul emerald was set into the pendant and necklace in France around the turn of the 20th century. This historic and remarkable emerald necklace is a wonderful addition to the National Gem Collection.

Mogul Emerald Necklace. From the Smithsonian Museum of Natural History.

Mogul Emerald Necklace. From the Smithsonian Museum of Natural History.

The Mackay Emerald. The stunning Mackay Emerald was mined in Muzo, Colombia. The finest emeralds are found in the region around Muzo and Chivor, Colombia.  These green gems were used by indigenous peoples for at least 1,000 years before the arrival of the Spanish conquistadores in the 16th century.  Although spurred primarily by their passion for gold and silver, the Spanish quickly recognized the potential of the exquisite green crystals and took control of the mines.  Emeralds became popular among European royalty and were shipped from the New World by the boatload.  The great richness of the Colombian mines led to a glut of emeralds in Europe, triggering a brisk trade of the gemstones to the Middle East and India.  The Mogul rulers in India were especially fond of emeralds and encouraged a vast gem cutting and jewelry industry.  Many finished pieces were traded back to Europe. The Mackay Emerald is the largest cut emerald in the National Gem Collection and is set in a pendant of diamonds and platinum designed by Cartier, Inc.  The Art Deco style necklace was a wedding gift in 1931 from Clarence Mackay to his wife, Anna Case, a prima donna of the New York Metropolitan Opera from 1909 to 1920.  The emerald weighs 167.97 carats and is set in platinum with 35 emeralds and 2,191 colorless round brilliant and step cut diamonds.  Mrs. Anna Case Mackay bequeathed the necklace to the Smithsonian in 1984, and it is on display in the Gem Hall at the National Museum of Natural History.

Mackay Emerald Necklace. From the Smithsonian Museum of Natural History.

Mackay Emerald Necklace. From the Smithsonian Museum of Natural History.

The Chalk Emerald. The superb clarity and color of the Chalk Emerald ranks it among the world’s finest Colombian emeralds. This outstanding 37.8-carat emerald exhibits the velvety deep green color that is most highly prized. The finest emeralds are found in the region around Muzo and Chivor, Colombia. These green gems were used by indigenous peoples for at least 1,000 years before the arrival of the Spanish conquistadores in the 16th century. Although spurred primarily by their passion for gold and silver, the Spanish quickly recognized the potential of the exquisite green crystals and took control of the mines. Emeralds became popular among European royalty and were shipped from the New World by the boatload. The great richness of the Colombian mines led to a glut of emeralds in Europe, triggering a brisk trade of the gemstones to the Middle East and India. The Mogul rulers in India were especially fond of emeralds and encouraged a vast gem cutting and jewelry industry. Many finished pieces were traded back to Europe. According to legend, the Chalk Emerald was once the centerpiece of an emerald and diamond necklace belonging to a Maharani of the former state of Baroda, India. It originally weighed 38.4 carats, but was recut and set in a platinum and gold ring designed by Harry Winston, Inc., where it is surrounded by 60 pear-shaped diamonds totaling 15 carats. It was donated to the Smithsonian by Mr. and Mrs. O. Roy Chalk in 1972 and is on display in the Gem Gallery at the National Museum of Natural History.

The Chalk Emerald. From the Smithsonian Museum of Natural History.

The Chalk Emerald. From the Smithsonian Museum of Natural History.

Resources and further reading

Smithsonian National Museum of Natural History. All of the information and images in the Notable Emeralds section was obtained from the NMNH.

Jewels: A Secret History. By Victoria Finlay.  An non-fiction adventure through time and place exploring the history of gems.

Emerald. From Wikipedia. An interesting entry describing the composition of emeralds, how they are valued, and where they are mined.

Gemstones of the World. By Walter Schuman.  Our go to book at Grimballs.