10.91 Ct. Green Tourmaline from Africa

One beautiful transparent 10.91 carat emerald cut green tourmaline is presented by The Natural Gemstone Company, with precise dimensions of 12.39 x 10.86 x 8.68 mm. The stone is faceted in an emerald cut, evaluated as very slightly included at eye level, with intense color intensity and an excellent polish. The gem originates from Africa and has been subjected to controlled heat treatment to enhance its hue. The combination of substantial carat weight, classic emerald cut proportions, and a high standard of finish defines this specimen as a fine example of gem quality tourmaline suitable for a range of fine jewelry applications.

The genesis of this tourmaline began millions of years ago during a prolonged interval of crustal activity that shaped the geological provinces of its African source region. Deep below the surface, granitic magmas intruded older formations and slowly cooled, concentrating volatile components such as water and boron in evolving melt pockets. As the residual magmas reached the final stages of crystallization, boron rich fluids migrated through fractures and miarolitic cavities, carrying with them alkali elements and trace metals. Under conditions of reduced pressure and gradually declining temperature, these fluids crystallized within pegmatitic zones, providing the chemical environment and space necessary for tourmaline to grow over extended periods.

Crystal growth proceeded layer by layer, with individual prisms expanding as the boron rich fluids supplied essential constituents. The green color in this specimen developed as iron and trace chromium or vanadium were incorporated into the crystal lattice during formation, producing the lively green seen in the finished stone. Slow growth within open cavities allowed for relatively clean crystallization, while brief interruptions in fluid flow produced the subtle internal features identified as very slightly included at eye level. These minute growth related characteristics record snapshots of the evolving conditions during mineralization, and they contribute to the individuality and natural provenance of the gem.

After recovery from the host rock, the rough piece was examined and oriented to maximize both color and yield, then carefully shaped into a classic emerald cut to emphasize clarity and depth of color. The emerald cut, with its broad step cut planes, was selected to create distinct color zoning and to present a deep, even face up color across the table. The cutter refined the proportions so that the finished gem measures 12.39 x 10.86 x 8.68 mm, balancing table size, depth, and pavilion angles to preserve light return and saturation. The excellent polish achieved on each facet enhances transparency and surface luster, while the faceting pattern and symmetry reveal the internal color in a controlled manner, producing the intense green that characterizes this tourmaline.

This stone is presented with transparency regarding enhancement and origin, the heat treatment applied is a standard practice to stabilize and intensify hue, and the African provenance reflects a long geological history and well established mining regions. For maintenance, gentle cleaning with warm water and mild detergent, followed by soft drying, will preserve the gem and its polish, and professional inspection of settings is recommended to protect the mounting. The Natural Gemstone Company stands behind the accuracy of the descriptive details, and encourages independent gemological review for those seeking formal documentation. This emerald cut green tourmaline combines geological narrative, technical precision, and careful craftsmanship, offering a well documented example of natural tourmaline formed over deep time.