Natural amethyst quartz (2023)Instituto Gemológico Español (IGE)
Inclusions in gems may provide very valuable information regarding their nature, as well as their origin and identity. Some inclusions are specific to certain gems.
Amethyst quartz inclusion (2023)Instituto Gemológico Español (IGE)
1. Amethyst
In the ocassions when we find the so-called “zebra stripes” or “tiger stripes” we can identify the gemstone as a natural amethyst.
Amethyst quartz inclusion (2023)Instituto Gemológico Español (IGE)
The tiger stripes are related to twinning in the crystal, typical in amethyst quartzs.
Goethite brooms inclusions in amethyst quartz (2017)Instituto Gemológico Español (IGE)
Goethite “brooms” are also very characteristic of amethysts.
Goethite brooms inclusions in amethyst quartz (2017)Instituto Gemológico Español (IGE)
Goethite is an iron oxide mineral, a weathering product of numerous iron-bearing minerals.
Horsetail in demantoid garnet (2023)Instituto Gemológico Español (IGE)
2. Demantoid garnet
Demantoid garnets from Russia might show the so-called “horsetail”.
Horsetail in demantoid garnet (2023)Instituto Gemológico Español (IGE)
It is formed by curved byssolite fibers clusters, emerging from a chromite crystal.
Lily pad in peridot (2023)Instituto Gemológico Español (IGE)
3. Peridot
Peridot shows a very distinct color but, if there is any doubt about it’s identity, it is common to find a very typical and exclusive inclusion.
Lily pad in peridot (2023)Instituto Gemológico Español (IGE)
It is known by the name of “lily pad”, as it is very evocative.
Lily pad in peridot (2023)Instituto Gemológico Español (IGE)
This inclusion is formed by a chromite, chrome diopside or chrome spinel crystal, surrounded by a disc-shaped fissure around it, which can be filled with different materials.
Trichites in tourmaline (2023)Instituto Gemológico Español (IGE)
4. Tourmaline
Tourmalines are very appreciated due to their versatility, related to their beauty and chromatic variety.
Trichites in tourmaline (2023)Instituto Gemológico Español (IGE)
Even though tourmalines might show a great variety of inclusions, but trichites are very characteristic.
Trichites in tourmaline (2023)Instituto Gemológico Español (IGE)
Trichites are thread-like cavities that run parallel to the length of the crystal. They are filled with liquid or gas bubbles.
Photo credits: Ana de Bustos Ruiz, José Alonso
Written by: Irene Gobet. Text revision: Marta del Teso, Almudena Gómez