Process of carving a sphalerite

The cutting of a sphalerite from the Picos de Europa is a meticulous process that seeks to highlight the aesthetic and optical properties of this mineral, especially its high refractive index and dispersion, which give it an exceptional brilliance. Below, I will detail the typical process:

1. Material Selection

• A piece of sphalerite of suitable quality is chosen, evaluating its color, clarity, size and the absence of significant fractures or inclusions.
• Sphalerites from Picos de Europa usually have colors ranging from yellow to red or brown, and the most transparent pieces are prioritized.

2. Initial Cut

• A diamond saw is used to cut the mineral into a more manageable shape and to remove impurities or damaged areas.
• During this step, the aim is to optimize the part and reduce waste, considering the orientation of future facets.

3. Design and Planning

• The design of the cut is planned, taking into account the optical properties of sphalerite.
• Due to its low hardness (3.5-4 on the Mohs scale) and its brittleness, a design that minimizes internal stresses is selected.

4. Preformed

• Using rotary or grinding tools, the mineral is given a basic shape, following the planned design.
• This step allows you to remove additional material and define the main facets.

5. Facet Carving

• A grinding machine with fine-grained abrasive discs is used to precisely sculpt the facets.
• Angles are carefully adjusted to maximize light refraction and dispersion.
• It is worked slowly due to the fragility of sphalerite, to avoid fractures.

6. Polishing

• The facets are polished with specific abrasive pastes, such as cerium or aluminium oxide, to obtain a perfectly smooth and shiny surface.
• Polishing improves transparency and highlights the brilliance of the mineral.

7. Final Inspection

• The piece is checked to ensure that all facets are symmetrical and well polished.
• The quality of brightness, dispersion and overall visual impact are evaluated.

8. Assembly (Optional)

• If intended for jewelry, sphalerite is mounted in a suitable setting to protect its edges, due to its fragility.

Cutting sphalerite is a challenging process due to its low hardness and fragility, but the results can be spectacular, especially when it comes to high-quality material such as that from the Picos de Europa.