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Article: The greatness of Coscuez, a unique Colombian emerald mine


The greatness of Coscuez, a unique Colombian emerald mine

The beauty of Coscuez and its unique nature have made it one of the favorite emerald extraction mines for local and foreign miners in this area of ​​Boyacá in Colombia. 

Located in the lush and green mountainous department of Boyacá, the Coscuez emerald mine covers an area of ​​46 hectares and is some 228 kilometers from Bogotá. 

The Coscuez mine is historically one of the most important emerald mines in the world, having been in operation for over 400 years and producing some of the finest emeralds in Colombia.

Stay and learn everything about this mythical mine, its history, how its emeralds lie, and why it is the favorite place for gemology experts and lovers of Colombian emeralds. 

The story of Coscuez 

The first records of emeralds in Colombia date back to a region called Somondoco (now Chivor) in 1537. However, it was not until 1833 when the concept of profitable 'open pit' mining was introduced that this activity began to flourish.

Emerald mining in Colombia has a history of more than 400 years and includes several mines distributed between the Departments of Cundinamarca and Boyacá, with the mines located in Boyacá being recognized as large producers, specifically in Muzo and Coscuez, separated only by 10 km from each other. distance. 

Although smaller than Muzo, the Coscuez mine has for over 400 years produced some of the best emeralds in the region, sometimes in quantities that have even surpassed the Muzo mine. In the mid-1980s, production from the Chivor region began to dry up, while that from the Coscuez mine picked up rapidly.

Today, the Coscuez mine has grown to become one of the largest emerald producers in Colombia and is rapidly gaining importance as a leading source of large and fine emeralds.  

Coscuez Emeralds

According to several studies carried out on the emeralds extracted in the coscuez mines, they have the following characteristics: 

  • Crystallization: Observations by local miners have suggested that the Coscuez emerald may exhibit more complex crystal forms than the Muzo emerald. Although both mines produce many simple prismatic crystal forms, a large number of emeralds of three, six or more individually terminated crystals are found at Coscuez. The faces tend to be shiny with little to no engraving. 

The Coscuez emeralds are said to be "famous for their exceptional green color" and their elongated crystals.

  • Color: In Colombia all the mines differ in the color of the emeralds due to the subsoil conditions. Sometimes the Coscuez crystals are vivid, clean and slightly saturated in color like those from Gachalà, sometimes the material is very bluish like Chivor, and sometimes there is absolutely no difference from Muzo in color and quality. 

However, there is one type of emerald that is commonly seen in Coscuez. This class of emerald from Coscuez can be described as strongly saturated, slightly bluish, and when the stone is green it has a medium-dark to very dark hue.

Often the tone is so dark that transparency and "life" are diminished. However, these stones are still very attractive, especially to those who appreciate strongly saturated color over brilliance and transparency. 

  • Physical properties: the properties of the emeralds extracted in Coscuez do not vary significantly from Colombian emeralds in general, since the type of physical conditions, and even climatology, of the mines in Boyacà are similar. 
  • Inclusions : A preliminary microscope examination of the Coscuez emeralds did not reveal significant differences in the number or type of inclusions between the Muzo and Coscuez emeralds. 

Emeralds from both sources have two- and three-phase inclusions and the typical internal features associated with Muzo material: "coal" inclusions of carbonaceous matter, as well as calcite, albite, pyrite, quartz, and (rarely) baryte, fluorite, and apatite. .

However, the main "garden" feature from Coscuez and other Colombian mines shows partially healed fractures and appears to be slightly more unidirectional than the Muzo stones.

Recognized emeralds from Coscuez 

Although perhaps hundreds of emeralds extracted from the Coscuez mines are marketed every day, there are certain stones that have stood out due to their large size or exceptional color: 

  • Emeralds from the museum of Madrid (1600): 550 carats of crystal emerald were sold to the Museum of Madrid in Spain, all the stones were extracted from the Coscuez tunnels.
  • The fine stone of Coscuez (1986): a 100ct crystal top stone from Coscuez sold in New York for over US$25,000 per carat.
  • Esmeralda ARE (2018) : was named “ÄRE Emerald”, in honor of a figure from ancient Colombian mythology responsible for the creation of the main sources of emeralds in the Boyacá region, the Fura and Tena mountains. The emerald has 25.97 carats and is considered one of the many large rough stones obtained in this place. 

Guinness Emerald: It was in Coscuez that the 1,759-carat Guinness Emerald Crystal was discovered, one of the largest gem-quality crystals in the world. Currently, it resides in the collection of the Bank of the Republic of Colombia.

Paula A. Bonilla

Social communicator and journalist from Sergio Arboleda University in Colombia. She is also a jeweler and is passionate about constantly learning about precious gems and national high jewelry.

Currently, she is working for one of Bogotá's most important jewelry stores, Emerald by Love. This jewelry store has over 40 years of experience and has 2 physical branches in the capital city of Colombia, located in the city center.

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