Emeralds, the green queens of gems, offer us the possibility of interpreting their origin, including the mine from which they were extracted.
Did you know that you can read an emerald?
The expert eye of the gemologist glimpses a myriad of inclusions. Observing an emerald under a microscope is a delight for gemology lovers. Although at first glance you can already see the different inclusions also called garden. But it is with the 10x magnifying glass and the gemological microscope that we will appreciate the diversity of minerals that can be found inside.
Steps to carry out a detailed and exhaustive study of emeralds
First we must observe it with the naked eye, with a slight movement of the stone under a beam of light to be able to appreciate it:
- The different shades
- Transparency
- Color saturation
Then, with the gemological or 10x magnifying loupe:
- We will look for cracks, fractures or breaks.
- We must observe if there is any inclusion that reaches the surface of the cut emerald.
polishing defects or not - We will look for glue bubbles or areas that show that it is formed by different materials, which will lead us to rule out doublets or triplets as gems.
- The existence of bubbles leads us to think that it could be a crystal.
Emeralds offer us the possibility of interpreting their origin.
Close observation under the microscope
We will continue with a thorough microscopic observation, for which the emerald will be immersed in alcohol and observed through the binocular microscope with the aid of episcopic and diascopic light halos.
We will combine different eyepieces and objectives to achieve high magnifications and focus on each of the inclusions and particular characteristics of each stone.
This observation is essential in order to be able to separate those of natural origin from those of synthetic origin. It is also essential to be able to determine their origin, and to be able to talk about Colombian emeralds, Muzo emeralds, Trapiche emeralds, African emeralds, Brazilian emeralds…
This observation is easier if the stone is not set in jewelry, such as emerald rings, bracelets or pendants. In this case, it will require more expertise in observation, more time, and placing the stone in very different positions in order to appreciate and view each side and face of the gem.
Information on the origin and formation process of emeralds
We will use both transmitted and reflected light, as both help us to observe the colors of the crystals hosted within the emeralds, and the transparency or opacity of the emeralds.
The most common crystals that we will find in the exhaustive observation of emeralds are actinolite, mica and calcite. In addition, biphasic and triphasic inclusions with negative crystals are characteristic of these stones.
All this provides the gemologist with extensive information on the origin and formation process of the emerald, determining its hydrothermal (Colombian) or metamorphic origin.
Emeralds of hydrothermal or Colombian origin.
Among the different inclusions found in Colombian emeralds are the following:
Muzo Emeralds:
Brownish parisite (exclusive of this region), calcite crystals (rhombohedron shape), black slate crystals.
Chivor Emeralds:
Pyrite (distinguished by its cubic shape and its characteristic metallic color) and transparent and colorless albitach prisms.
Colombian green emeralds:
Elongated and serrated three-phase (liquid-gas) inclusions.
Emeralds of metaphorical origin
In emeralds of metamorphic origin the most characteristic inclusions are the following:
- Actinolite in the form of green reeds. They usually have very elongated and prismatic shapes.
- Biotite in the form of hexagonal plates and brownish color.
- Very fine tremolite needles with green prismatic habits; very characteristic of emeralds from Zambia.
- Opaque and dull black chromite in the form of octahedrons, found in South African emeralds.
These wonders of nature host in their interior other beautiful minerals and lead us to discover the formation process they underwent millions of years ago.
