16.76 Ct. Ametrine from Ceylon (Sri Lanka)

This single transparent 16.76 carat radiant shape bi color ametrine measures 15.42 x 13.43 x 11.31 mm and offers a rare and immediately striking presence for the discerning collector or custom jeweler. The radiant cut balances brilliant facets across the crown with trimmed corners that maximize scintillation while retaining a modern rectangular outline. The stone displays medium color intensity with distinct bi color zoning, where warm golden citrine tones transition into cool violet amethyst tones. Clarity has been evaluated as very slightly included at eye level, meaning that inclusions are minimal and do not distract from the gem when viewed without magnification, supporting excellent transparency and allowing light to move freely through the stone. The polish is excellent, providing crisp facet junctions and lively surface reflection. Enhancement has been disclosed as heat treated, a common and stable treatment used to refine and stabilize color in quartz varieties, and provenance is Ceylon Sri Lanka, which adds provenance interest for collectors familiar with regional gem histories.

From a technical and grading perspective this ametrine has attributes that educated buyers will recognize as value drivers. The 16.76 carat weight and the substantial dimensions produce a platform for color zoning to be read easily and for the radiant cut to deliver an appealing balance of brilliance and fire. Very slightly included evaluated at eye level indicates that the stone ranks well when considering clarity versus price, because minute internal features do not impact visual performance unless examined closely. Medium color intensity for ametrine is often preferred because it preserves the inherent contrast between the citrine and amethyst areas, avoiding the washed or overly dark appearance that can occur with other intensity levels. Excellent polish is important for both aesthetics and light return, and it assures that facet edges are sharp and that the pavilion and crown are properly finished to support optimal optical behavior. The disclosed heat treatment is stable under normal wear and cleaning, and transparency about this enhancement is part of our standard appraisal and sales practice at The Natural Gemstone Company.

When planning a custom piece, the bi color nature and radiant geometry of this ametrine present multiple creative and technically sound options. For a ring or pendant design that highlights the color transition, orient the stone so that the color division runs along the long axis of the setting, making the bi color contrast immediately readable from face up. Pairing choices should be deliberate to either emphasize contrast or create harmony. A clean white diamond halo and diamond shoulders will increase overall brilliance and act as neutral light amplifiers, making both the purple and yellow areas appear more vivid without adding competing color. To create a tonal echo, consider small calibrated amethyst melee on the purple side and citrine or warm champagne diamonds on the golden side, set in a graduated or split halo that mirrors the center stone division. For high contrast and a contemporary statement, use polished platinum or 18 karat white gold for the purple side to cool the violet, and 18 karat yellow gold for the golden side to enrich the citrine tones, executing a two tone bezel or gallery that reflects the ametrine’s internal dichotomy in the metalwork. Colored sapphires and spinels are also excellent complements. A line of yellow sapphires will reinforce warmth without matching too closely, while violet or purple spinel will echo the amethyst hue with greater hardness stability. For a more dramatic color play, small green tsavorites set as accent stones can introduce a triadic color contrast that highlights both the purple and yellow areas by visual separation and vibrancy.

Practical considerations for wear and care should be built into the design to preserve beauty and longevity. Quartz has a Mohs hardness of approximately 7, which is suitable for everyday jewelry when the stone is protected by a secure setting, but it is not as hard as corundum or diamond, so good practice is to avoid settings that leave the table or corners exposed to direct knocks. The radiant cut with its trimmed corners benefits from protective prongs or a bezel that can safeguard the pavilion and corners while still allowing the color zoning to be admired. Heat treated quartz is stable, but avoid exposing the piece to high temperatures after setting, and clean with warm soapy water and a soft brush, rinsing thoroughly and drying with a soft cloth. We document the clarity evaluation, measured dimensions, carat weight, cut description, color intensity grading, polish grade, treatment disclosure, and origin with images and a written report on request. The Natural Gemstone Company stands behind this specimen with full disclosure and tailored service for bespoke design work. If you would like further technical imagery, facet maps, or a design consultation to visualize how this 16.76 carat bi color ametrine will perform in a specific custom setting, we can provide CAD visualizations and partner you with experienced designers to realize a piece that preserves the gem’s optical character and meets your aesthetic and practical requirements.