4.02 Ct. Ametrine from Brazil

This specimen from The Natural Gemstone Company is a finely fashioned 4.02 carat cushion shape bi color ametrine, with precise dimensions of 11.71 by 8.33 by 6.82 mm, yielding a length to width ratio of approximately 1.41 and an overall depth ratio of approximately 68 percent relative to the average of length and width. The cutter employed a mixed brilliant cut, combining a brilliant style crown with a pavilion and girdle geometry designed to maximize scintillation while preserving the natural bicolor zoning that defines ametrine. The transparency is exceptional, described as eye clean when evaluated at eye level, and the stone exhibits a medium color intensity across both amethyst and citrine zones. Surface finish is of an excellent polish grade, executed to tight facet junction tolerances for optimal light return. The piece has been heat treated to stabilize and enhance color transition, and the material is sourced from Brazil, reflecting recent supply diversity in addition to the historical Bolivian provenance associated with ametrine.

From a lapidary perspective the mixed brilliant execution is intended to reconcile two competing objectives, brilliance and color separation. The crown is cut with a classical brilliant facet layout, utilizing small star and upper girdle facets to generate flash and scintillation, while the pavilion incorporates a hybrid of brilliant and shallow step facets that enhance directional light return without blurring the color interface. During preforming the cutter oriented the rough to align the natural color boundary parallel to the cushion long axis, a deliberate choice that preserves a sharp dichroic band between purple and golden areas when viewed face up. Facet angles were calibrated to the refractive index of quartz family material, taking into account dispersion constraints in order to prevent washout of hue. Final polish was achieved using diamond abrasives on the early stages and a cerium based polish on the last lap to produce mirror smooth facet planes and minimal microscopic abrasions, which contributes to both the perceived brilliance and to the durability of the surface under wear.

In terms of gemological characteristics and traditional significance, ametrine represents a unique fusion of amethyst and citrine chemistry within a single crystal, historically treasured for both aesthetic and talismanic reasons. While the most famous historical source is the Anahi mine, this example from Brazil demonstrates how modern occurrences supply material that can be expertly cut to the same cultural and jewelry contexts. Traditional uses include signet and statement rings where the clear delineation of color is shown off in large table facets, as well as vintage style pendants and brooches that favor cushion silhouettes. Technically minded buyers will value the balance between color zoning and symmetry, since effective settings often require orientation that highlights the color split, either along the finger axis in rings or centered in a pendant. Mechanically the material is quartz, with a hardness near seven on the Mohs scale, offering good resistance to everyday wear when properly set, while still requiring reasonable care to avoid abrasion and thermal shock, especially given the heat treated nature of the stone.

As custodians of fine material The Natural Gemstone Company provides this ametrine with careful consideration for setting and conservation. At 4.02 carats and 11.71 by 8.33 by 6.82 mm, the stone is well suited to both bespoke prong mounted designs that expose the pavilion for maximum light entry, and bezel or closed back settings that emphasize the cushion silhouette and protect the girdle. For clients seeking technical documentation we can supply high resolution imaging showing the color boundary and facet architecture, and we document the heat treatment enhancement as part of our transparency policy. Recommended setting orientation is with the bicolor interface running along the long axis for a balanced face up presentation, though creative designers may elect to orient the crown to create gradient effects under diffuse illumination. Care guidance includes avoiding sudden temperature fluctuation and strong mechanical shocks, occasional gentle cleaning with warm soapy water and a soft brush, and avoiding harsh chemical cleaners. For further technical consultation on mounting, certification, or bespoke design options please contact our gemological team at The Natural Gemstone Company, we are available to provide measurements, high magnification imagery, and tailored recommendations for integrating this cushion bi color ametrine into an heirloom quality piece.