“Trapiche” is a type of milling wheel used to process cane sugar. This gemstone was named after it because of the similarity of appearance between the spokes of the mill and the growth pattern of the gemstone’s inclusions.
True trapiches form where geothermal waters meet a carbonaceous host rock. During mineral growth, the gem ceases to grow along the rough edges of the crystal. Instead, it grows only on the smooth faces. This leads to the gemstone growing in sectors independently from one another, and allows a second mineral inclusion to form within the gaps, thus forming the unique trapiche pattern.
Since the geological conditions necessary to create trapiche gems are uncommon, trapiche gems are some of the rarest specimens on Earth. Trapiche Gems are immensely rare, and are most often found in emeralds. However, trapiche growth patterns may also be found in other gemstones.