1.82 Ct. Moonstone from Madagascar

This 1.82 carat oval rainbow moonstone is a study in measured proportions and refined lapidary technique, presented by The Natural Gemstone Company. The gem measures 8.60 by 6.93 by 5.44 millimeters, and is fashioned in a mixed brilliant style to balance vibrant adularescence with faceted scintillation. Clarity is graded very slightly included when examined at eye level, a designation that speaks to the stone having a small number of internal features that are restrained in size and distribution, and that do not impede the passage of light. Color intensity is light, which permits a translucent body that supports the play of internal light rather than obscuring it, and the polish is excellent, reflecting meticulous finishing that preserves facet junctions and maximizes surface luster. There has been no enhancement applied, and the piece is of Madagascar origin, a provenance that is known for moonstones with clearly defined albite lamellae and strong spectral flash.

The faceting deserves particular attention, because mixed brilliant cutting for moonstone is a deliberate choice that requires control of facet geometry relative to the mineral internal structure. In this oval, the crown exhibits a modified brilliant facet arrangement, optimized to capture and channel incident light across the orthogonal lamellae that produce adularescence, while the pavilion employs a hybrid of shallow step facets and truncated brilliant facets to manage internal reflection paths and to protect the sensitive cleavage planes. The length to width ratio is approximately 1.24, which yields a classic oval silhouette that preserves symmetry and allows an extended arcing flash to travel parallel to the major axis. Depth to average diameter is approximately 70 percent, a slightly deep proportion that concentrates the adularescent band and enhances color saturation when the stone is viewed at the optimal angle. The cutter has left the girdle uniform and carefully faceted to avoid stress concentrations, and the excellent polish ensures that facet intersections remain crisp, which is essential for predictable optical behavior in a stone with layered internal microstructure.

The internal inclusions are the defining characteristic that give this rainbow moonstone its unmistakable signature. The signature is composed predominantly of exsolution lamellae of albite, appearing as thin, subparallel platelets that form from polysynthetic twinning during the crystal growth and cooling process. These platelets are responsible for the coherent scattering that produces the silky adularescent sheen, and in this specimen they are complemented by localized microveils and minute feather like fractures that act as diffraction elements. The interplay of lamellar spacing and microfracture geometry yields discrete spectral separation, producing small areas of violet, blue, green, and rose within the overall adularescent band. Under 10 times magnification the lamellae present as narrow, alternating light and dark striations with occasional tiny inclusions of the host matrix, while at eye level the stone maintains a clean appearance with only selective, characterful features visible. Rather than detracting, these inclusions are the mechanism of the gem charisma, they orient and define the flash, ensuring that each movement reveals a new configuration of color and texture unique to this piece.

Optically the specimen benefits from its semi transparent body and light color intensity, which create an internal environment conducive to both scattering and transmission. Because the albite lamellae are oriented in a preferred direction, the mixed brilliant faceting has been aligned to present the lamellar planes to incoming light at angles that favor thin film interference. Variations in lamellar thickness across microscopic distances cause selective constructive interference of different wavelengths, and this is the scientific basis of the rainbow designation. The blue and green flashes correspond to regions where the lamellae spacing amplifies shorter wavelengths, while thinner sections and diffraction at microveils produce warmer pink and orange accents. The absence of any enhancement means these colors are intrinsic, they arise from natural exsolution and isomorphic layering that occurred during the cooling history in the Madagascar deposit. The result is a faceted moonstone that combines the directional shimmer typically associated with cabochon cutting, with faceted brilliance that adds scintillation and surface sparkle.

From a practical and collecting perspective this 1.82 carat oval is exceptionally versatile and suitable for both bespoke jewelry and technical collections. Its mixed brilliant cut makes it an excellent candidate for settings that allow light transmission through the pavilion, such as halo or open backed mounts, while the moderate depth and balanced proportions offer secure bezel or prong setting options without compromising the adularescent play. Care recommendations to preserve the internal structure include avoiding thermal shock, aggressive chemicals, or mechanical impact, and cleaning with mild soap and a soft brush, while ultrasonic cleaners should be used with caution due to the presence of internal microveils and cleavage planes. The provenance from Madagascar, the unenhanced status, and the documented clarity grade make this stone both a scientifically interesting specimen and an appealing design element. For buyers seeking a gemstone with a documented technical profile and a signature internal personality, this rainbow moonstone is presented with full confidence by The Natural Gemstone Company, and our team is available to provide additional photomicrographs, orientation diagrams, or setting recommendations on request.