What is a Trapiche Emerald?What is a Trapiche Emerald?

Emerald Specialist Mini Course

What is a Trapiche Emerald?

Many books and articles cover the beautiful emerald, the most well-known member of the beryl family. You can learn about its rich green tones, the jardin or "garden" of inclusions that often help identify a stone's origins, its unique cutting properties, and the treatments it receives. However, you'll find very little information about the extremely rare trapiche emerald.

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trapiche emerald - close up
Trapiche emerald. Photo by Jeffery Bergman, © EighthDimensionGems. Used with permission.

What Do Trapiche Emeralds Look Like?

These emeralds get their name from the trapiche (pronounced tra·PEE·che), a grinding wheel used in Colombia, South America. In the regions where these gems are often found, people use these wheels to process sugarcane. As you can see in the following photo, some of these gems resemble a spoked wheel with a hexagonal core.

hexagonal core
Note the hexagonal core of this trapiche emerald, typical for the growth of emeralds. Photo courtesy of Marc Gering, JazzanJewels.

Please note, however, not all of these gems have that hexagonal "hub." Some enthusiasts believe trapiche emeralds from one mining area display the core, while those from another don't. Based on my research and conversations with dealers, the presence or lack of a core doesn't appear to indicate origin.

Also, keep in mind that other gemstone species — such as rubies, sapphires, and aquamarines — can occur in rare trapiche shapes.

Are Trapiche Emeralds "Star Stones?"

Despite its starlike appearance, this unique "spoked" pattern isn't a case of asterism (the "star stone" effect). However, trapiche emeralds may reveal chatoyancy, a "cat's eye" effect. Parallel growth tube inclusions can create a cat's eye in the "pie-shaped" sections as well as, rarely, along the length of whole cabbed trapiche emeralds. Expert lapidaries can orient and cut these stones to bring out this effect.

trapiche emerald - cat's eye
Trapiche emerald showing cat's eye in segments. Photo by Jeffery Bergman, © EighthDimensionGems. Used with permission.

How Does a Trapiche Emerald Form?

During the formation of an emerald crystal, black carbon impurities may enter the gemstone mix. Because of emerald's hexagonal crystal structure, these impurities may fill in at the crystal junctions, forming a six-point radial pattern. In some trapiche emeralds, inclusions of albite, quartz, carbonaceous materials, or lutite may outline the hexagonal emerald core. From there, they extend in spokes that divide the surrounding emerald material into six trapezoidal sectors.

The central, tapered emerald core first grows under hydrothermal conditions, but should these conditions slow or even stop for some time, impurities may enter the mix. As growth conditions resume, both emerald and, for example, albite may form. Although the hexagonal prism faces of the core crystal can maintain their uniform growth, producing pure emerald, albite fills the areas growing from the edges, between the prism faces. This results in six sectors of clear emerald and six of a combination, predominantly albite with some emerald. Thus, the central core and the six surrounding trapezoidal sectors of a trapiche emerald comprise a single, untwinned crystal."

trapiche emerald - Somewhere in the Rainbow Collection
"Somewhere in the Rainbow Collection," trapiche emerald. Photo by Jeff Scovil, © EighthDimensionGems. Used with permission.

Although the hexagonal core may often be colorless, transparent beryl, it can also be green. In a 1970 analysis of Muzo, Colombia's trapiche emeralds in American Mineralogist, K. Nassau and K. A. Jackson found their principal coloring agent was vanadium."

Trapiche Emerald Gallery

With or without cores, trapiche emeralds make lovely gems.

trapiche emerald - no core
A trapiche emerald with no central core. Photo courtesy of Marc Gering, JazzanJewels.

Let your imagination run free when you gaze upon these precious gems. For example, in the stone below, I see a spider.

spider gem
Photo courtesy of Marc Gering, JazzanJewels.

In this gem, I see a moth.

moth gem
Photo courtesy of Marc Gering, JazzanJewels.

Trapiche emeralds can get very large and may even weigh several grams.

rough emeralds
Photographs courtesy of Mr. Farooq Hashmi, Intimate Gems.

Sources of Trapiche Emeralds

People long believed only Colombia produced trapiche emeralds, at the Muzo and Peñas Blancas mines, but these gems have also been found in Brazil. Also, a light grayish green beryl, 13.74 cts, with a trapiche-like structure was discovered in Madagascar.

Trapiche Emerald Treatments

Recent visitors to the Colombian mines have reported the sale of obviously treated material presented as natural. Keep in mind that emeralds commonly receive various treatments and enhancements, and trapiche emeralds are frequently oiled or impregnated with epoxy.

You may also encounter imitation or simulated trapiches, such as a colorless beryl with a plastic coating imitating a trapiche pattern.

Wilma Van Der Giessen Collection - trapiche emeralds
"Wilma Van Der Giessen Collection," trapiche emeralds. Photo by Jeffery Bergman, © EighthDimensionGems. Used with permission.

Marc Gering

Marc Gering has done lapidary work since the early 1990s. You can see his gems at jazzanjewels.com. He began with cabochons, then — when that wasn’t challenging enough — bought a faceting machine and taught himself the art of faceting. In the late 1990s, he turned his hobby in a different direction to patent two optics-related inventions.

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