13.19 Ct. Ametrine from Ceylon (Sri Lanka)

This specimen is a transparent bi color ametrine weighing 13.19 carats, presented in a classical emerald cut, with precise dimensions of 14.97 by 11.34 by 10.08 millimetres, yielding a depth ratio of approximately 67 percent, a proportion that supports strong light return for step cut faceting. The gemstone exhibits medium color intensity across its dual tones, with a golden yellow occupying the table and central planes, transitioning to a saturated violet to purple at opposing table edges and cut corners, consistent with the characteristic bicolour zoning of ametrine. Clarity is recorded as very slightly included, evaluated at eye level, indicating only minor natural inclusions that do not materially interrupt transparency or reduce visual appeal when set. The piece has received an enhancement by controlled heat treatment to stabilize and balance the color distribution, and it displays an excellent polish with crisp facet junctions and minimal surface abrasion, attributes that maximize both brilliance and the hall of mirrors effect typical of well-executed step cuts. Origin is recorded as Ceylon, Sri Lanka, and provenance is available on request from The Natural Gemstone Company.

From a lapidary perspective the emerald cut chosen for this ametrine is both deliberate and functional, capitalising on long rectangular step facets to emphasize the linear colour transition and to create broad reflective planes that showcase the stone’s internal colour zoning. The cutting style uses elongated concentric steps on the crown and pavilion, a moderate table plane to emphasize the central yellow, and truncated corners that aid in practical durability without compromising the aesthetic symmetry. The step facets produce parallel light returns rather than scintillation, favouring even flashes and a stratified light pattern that accentuates the dichroic effect between the yellow and purple zones. The depth proportion near 67 percent supports adequate pavilion volume, preventing excessive windowing, and the symmetry of the facet arrangement ensures the bi-color interface reads consistently from multiple viewing angles, a desirable trait in larger statement gems intended for both ring and pendant applications.

Clarity assessment reflects the gem’s very slightly included status at loupe and eye level, which in quartz family stones typically corresponds to minute crystal inclusions, fine veils, or localized negative crystals that remain well-dispersed. These internal characteristics are inherent to natural growth and, in this example, are positioned such that the emerald cut’s broad facets minimize their visibility while preserving overall transparency. The excellent polish noted in the report indicates that facet planes were finished to a high standard, producing clean facet junctions and a smooth girdle profile, which together optimize light transmission and minimize optical disturbances. The heat treatment applied is a stable, industry-standard process for ametrine, undertaken to refine the balance between the yellow and purple zones and to reduce any unwanted greenish or brownish undertones, while leaving the natural zoning pattern intact. For the discerning buyer, the combination of medium color intensity, step-cut faceting, and careful polish yields a gem that is both visually compelling and technically robust.

In practical jewellery engineering terms this 13.19 carat emerald cut ametrine adapts to a wide range of settings and stylistic approaches, making it an excellent choice for both casual and formal applications. The emerald cut’s truncated corners and rectangular silhouette read well in traditional four-prong and bezel mounts, offering a balance between exposure and protection for daily wear. For a statement ring the depth and table dimensions allow the stone to sit with strong presence in a solitaire or halo configuration, halo designs can enhance perceived size and provide complementary contrast when set in yellow gold to warm the golden field, or in rose gold to emphasize the transition warmth, while white metals such as platinum or white gold will modernize the palette and emphasize the purple zoning. The stone’s size and clarity also make it ideal for pendants and brooches where the play of color can be viewed in multiple lighting environments, and for men’s signet or dress rings where the elongated geometry and robust proportions offer masculine balance without losing optical refinement.

At The Natural Gemstone Company we present this ametrine for aficionados who appreciate technical quality alongside aesthetic versatility. The specimen’s weight, measured dimensions, well-executed emerald cut, medium color intensity, and excellent polish together create a piece that functions equally well in elevated everyday wear and in formal, bespoke commissions. Its Mohs hardness of approximately seven, typical for quartz species, advises routine care to avoid sharp blows and to prevent abrasion from harder materials, but the emerald cut and truncated corners provide practical advantages for secure setting. For custom work our team can provide setting recommendations, CAD renderings, and mounting options that preserve the optical axis of the bi-color interface while ensuring mechanical stability. Please contact The Natural Gemstone Company for high resolution images under different lighting conditions, additional documentation on the heat treatment and origin, or to discuss custom bezel, prong, or mixed-metal designs tailored to this stone’s particular color orientation and cut geometry.