Natural Ametrine · 17.95 ct · Octagon · Bolivia · Unheated

This natural Ametrine weighs 17.95 carats and is fashioned in a substantial octagonal mixed cut, presenting the characteristic combination of purple and yellow colour zones for which this bicoloured Quartz variety is known.

Measuring approximately 17.0 × 13.0 × 9.3 mm, the gemstone offers considerable size and a strong face-up presence. Its broad octagonal outline and substantial depth provide an effective presentation of both the internal colour zoning and the overall transparency of the material.

The gemstone displays approximately 80% light pinkish-purple coloration and 20% light orangy-yellow coloration. The predominantly purple portion gives the stone its principal visual identity, while the contrasting yellow zone introduces a distinctive second colour component and clearly expresses the natural bicoloured character of Ametrine.

Ametrine is a naturally occurring variety of Quartz (SiO₂) in which Amethyst-type purple and Citrine-type yellow to orange colour zones coexist within a single crystal. The visual appeal of the material depends strongly on the distribution, contrast and orientation of these differently coloured growth zones.

This specimen is transparent and presents a clarity comparable to approximately VS1, with only relatively limited natural inclusions and internal growth features visible under magnification. The clean internal appearance allows the subtle colour zoning to remain clearly visible and contributes positively to light transmission and overall brightness.

The octagonal mixed cut has been selected to provide a broad viewing area across the bicoloured material. Its facet arrangement creates internal reflections across both colour zones while maintaining a strong geometric presentation.

Cut quality is assessed as Good to Very Good, with Fair to Good symmetry and Good polish. The polished facet surfaces produce an attractive vitreous luster, while the large dimensions and transparent body give the gemstone considerable visual presence.

There are no indications of heating and no indications of any other treatment. The purple and yellow colour zones are therefore presented in their naturally observed state without documented enhancement.

This specimen is recorded as originating from Bolivia, the locality most closely associated with significant natural Ametrine deposits and commercial gem-quality production.

With its substantial size, high transparency and clearly visible combination of light pinkish-purple and orangy-yellow colour zones, this natural Ametrine offers an attractive expression of one of Quartz’s most distinctive natural colour combinations. Its large octagonal form makes it particularly appealing for a statement jewellery design or a carefully selected gemstone collection.