20.17 Ct. Aquamarine from Brazil

This aquamarine is a museum caliber, transparent 20.17 carat emerald cut blue aquamarine, offered with exact dimensions of 18.80 by 15.20 by 9.52 mm. The sheer carat weight is the first feature that signals premium status, as aquamarine tends to command significant price escalation as clean, well colored material reaches the 20 carat class. At 20.17 carats the stone presents a commanding face up presence, with a rectangular table and long linear facets that maximize the apparent surface area, and a depth of approximately 56 percent, a proportion that balances light return and color saturation for an emerald cut. The medium color intensity is evenly distributed, producing a pure, cool blue that photographs as bright yet maintains the gemaceous subtlety that collectors prize, and the transparency is excellent, allowing the step cut planes to act as a series of reflective mirrors that emphasize tone and internal clarity rather than creating excessive scintillation.

The cutting and finishing of this piece are executed with technical precision, the emerald cut expressed as a classical step cut with broad crown steps, a large rectangular table, and well defined pavilion steps that yield a focused, linear flash of light. The corners are gently truncated to standard emerald cut geometry, which improves durability and provides optimal lapidary recovery for a rough of this size. Facet junctions are crisp, and the excellent polish enhances the luster without introducing microscopic polish lines that could interfere with the hall of mirrors effect characteristic of high quality step cuts. With a refractive index in the range typical for beryl, approximately 1.577 to 1.583, aquamarine does not exhibit high dispersion, so the cutter has emphasized proportion and facet symmetry to produce broad flashes of white light and to accentuate the blue hue rather than create small scintillating sparks, a choice that suits the gemological character of aquamarine and preserves a refined, elegant presentation.

Clarity for this specimen is graded as eye clean at normal viewing distances, a critical characteristic for step cut gems where inclusions, if present, are often revealed in large, planar facets. The absence of visible inclusions allows the eye to travel uninterrupted across the stone, showcasing subtle color zoning only when tilted under light, an attribute that attests to both the quality of the rough and the lapidary strategy. The piece has undergone a standard heat treatment, a stable enhancement commonly used in aquamarine to reduce greenish tones and refine a true blue, a treatment that is widely accepted in the trade and does not impair the gem's stability under normal wearing conditions. Origin is Brazil, a provenance associated with good crystallinity and favorable coloring in aquamarine, and the combination of Brazilian origin, natural transparency, and professional heat enhancement results in a gem that is both technically sound and visually appealing.

Presented by The Natural Gemstone Company, this 20.17 carat emerald cut aquamarine represents premium quality through an intersection of size, proportion, clarity, and finishing. The substantial carat weight affords design flexibility, allowing for a solitaire setting that showcases the stone as the primary visual element, or for incorporation into more complex designs where the stone must hold its own against complementary diamonds and metals. For connoisseurs and design professionals seeking a high grade aquamarine that combines gemological integrity with refined cutting choices, this specimen offers a rare combination of large mass, eye clean clarity, medium but well distributed color intensity, and meticulous polish, a combination that is difficult to find at this scale. For further technical details, documentation, or to discuss custom mounting and certification options, our gemology team at The Natural Gemstone Company can provide measurements, lighting condition images, and advice on optimal settings to preserve the mechanical integrity and visual performance of this exceptional aquamarine.