6.09 Ct. Bi Color Ametrine from Ceylon (Sri Lanka)

This parcel presents a transparent 6.09 carat, emerald cut, bi color ametrine, with exact dimensions 14.96 x 9.60 x 6.23 mm, cut to an elongated rectangular outline and executed in a classical emerald step cut. The pavilion and crown are composed of broad parallel facets that favor large, even color planes, while the generous table allows an unimpeded window into the stone to evaluate zoning and clarity. The piece exhibits intense color intensity across the amethyst and citrine zones, and assessment at eye level yields a clarity grade of very very slightly included. Facet junctions are sharply defined, symmetry is precise for an emerald cut of this size, the girdle is consistent and neither over nor under faceted, and the overall polish is excellent, producing crisp facet reflections and clean light return. Origin is Ceylon Sri Lanka, and enhancement by controlled heat treatment has been applied to stabilize and intensify the color contrast within the natural quartz matrix.

The genesis of this ametrine spans millions of years, beginning deep within silica rich, metamorphosed crustal domains where hydrothermal circulation introduced iron bearing fluids into open cavities and fissures. Under conditions of elevated temperature and pressure, clear quartz nucleated and grew as euhedral crystals, incorporating trace iron into the silica lattice. Subsequent fluctuations in the thermal regime produced localized redox gradients within a single crystal, creating adjacent regions where iron centers underwent differing valence states and radiation histories. In reduced zones the defects and intervalence charge transfers produced the characteristic purple of amethyst, while in oxidized or heat influenced regions the iron related color centers shifted toward the warm yellow of citrine. These juxtaposed color centers became locked into the quartz lattice as growth ceased and the crystal cooled, preserving a permanent bi color zoning that records the dynamic thermal and chemical microenvironment of its formation. Over geological time the host rock was uplifted and exposed, and only after careful recovery and lapidary selection did this particular crystal reveal the optical separation and balance necessary to produce an aesthetically and commercially desirable ametrine.

The choice of an emerald step cut for this specimen is a deliberate technical decision to maximize the stone s optical narrative and to manage light behavior across the two color zones. Step facets create broad flash reflections and accentuate planar color separation, allowing the eye to appreciate large, saturated fields of purple and yellow without the visual noise introduced by numerous small facets. The crown height and table percentage have been calibrated to balance internal reflection and external brilliance while preserving depth for the color zoning to manifest as separate but harmonious planes. The cutter oriented the bi color interface parallel to the table face, an alignment that yields a controlled dichroic effect when the stone is viewed face up, and a more blended transition when rotated, which provides dynamic visual interest in jewelry applications. The clarity grade reported as very very slightly included evaluated at eye level indicates only minute phantoms and healed fractures that do not compromise structural integrity or optical performance, and under loupe magnification these inclusions are subsidiary to the gem s overall transparency. Heat treatment disclosure is transparent, it has been applied to refine and unify the citrine component and to enhance color contrast, a standard and accepted practice in the trade that increases market desirability without materially altering the gem s natural origin.

Assembled and offered by The Natural Gemstone Company, this ametrine is presented with full provenance notation relating to Ceylon Sri Lanka and with treatment disclosure for heat enhancement. The weight and dimensions allow a variety of setting options, with the emerald cut dimensions particularly well suited for bezel and low profile four prong settings that protect the elongated corners while showcasing the broad table and stepped pavilion. For a ring intended for daily wear we recommend a protective setting that minimizes lateral impact to the corners and limits exposure to abrasive contact, while maintaining a slight elevation to allow light to enter through the pavilion for optimal color play. Paired with fine white melee or tapered baguette side stones the step cut geometry harmonizes and reinforces the directional facet logic, while warm metal choices such as 18 karat yellow gold will sympathetically echo the citrine plane and platinum or white gold will emphasize the amethyst plane and overall contrast. Routine care is straightforward given quartz hardness of seven on the Mohs scale, cleaning with warm soapy water and a soft brush is sufficient, and avoid sudden thermal shocks or prolonged exposure to strong acids. For collectors and connoisseurs who value geological narrative as well as lapidary precision, this bi color ametrine is an instructive and attractive specimen, and our team at The Natural Gemstone Company is available to provide additional imaging angles, microscopic inclusion photographs, and custom setting consultations to ensure the final presentation honors both the technical merits and the deep time story encapsulated in this stone.