The formation of Colombian emeralds is a scientific anomaly. Emeralds are composed of a rare beryllium element found in very small amounts in the Earth’s crust. What separates emeralds from other gemstones is the presence of chromium and/or vanadium. Trace amounts of these elements cause an emerald’s green color. It is extremely rare for these two elements to ever be found in the same location.
The Colombian emerald beds are unique because of the tectonic shifts that created the Andes Mountains, which was key in exposing raw beryllium, chromium, and vanadium together. The tectonic movements forced the materials in liquid and gaseous states into the cracks of a sedimentary medium. Because of this, Colombian emeralds are the only emeralds in the world that are found in sedimentary host rock instead of in igneous rock. The process by which Colombian emeralds crystalized in the absence of volcanic activity remains a mystery, but it is why Colombian emeralds are considered the purest and (sometimes by some geologists) the only “authentic” emeralds in the world.