82.19 Ct. Greenish Yellow (Lemon Quartz) Quartz

This listing presents one transparent lemon quartz, oval shape, 82.19 carat, dimensions 34.70 x 25.07 x 17.48 mm, mixed brilliant faceted cut, color described as greenish yellow with intense color intensity, clarity grade eye clean at normal viewing distance, excellent polish, no enhancement, origin unknown. The mixed brilliant designation in this instance refers to a design that marries a brilliant facet arrangement on the crown with a modified pavilion architecture that favors broad, elongated pavilion facets, this combination yields a balance between maximum return of light and preservation of color saturation, the oval outline permits a slightly larger table than a round equivalent which increases the apparent size while preserving scintillation, the precise proportioning of table size to crown height and pavilion depth is calibrated to the optical constants of quartz, enabling efficient light capture and focused return for strong face up brilliance.

From a structural optics perspective the sparkle of this specimen is the result of three converging factors, the intrinsic crystal properties of quartz, the large physical volume and the exacting facet geometry applied by the cutter. Quartz has a trigonal crystal structure and a refractive index approximately in the range 1.544 to 1.553, with birefringence near 0.009, these values define a critical angle and internal reflection regime that differs from higher dispersion gem materials, while quartz dispersion is modest, around 0.013, the mixed brilliant faceting maximizes scintillation by creating many high contrast facet junctions that alternate light and dark flashes as the stone moves, the pavilion facets are cut to angles that promote total internal reflection across a broad range of incident angles, the crown facets are then proportioned to refract and redirect that internally reflected light through the table and crown facets, the result is a lively, focused brilliance and a finely tuned pattern of flash that reads as more intense than dispersion alone would predict.

Technical quality is further evidenced by the excellent polish and tight facet junctions which minimize light loss at the surface and eliminate microscale scattering which would otherwise degrade both brilliance and transparency. The cutter oriented the rough to align the long axis of the oval with the crystal habit to reduce stress related birefringence visibility, the orientation also preserved the most saturated material during preforming, the girdle shows uniform thickness which aids secure setting without sacrificing optical performance, the pavilion and crown facet sizes are balanced to produce a pleasing contrast pattern that enhances face up color while maintaining depth and window control, the eye clean clarity means that the internal volume is effectively free of inclusions that disrupt internal light paths, together these characteristics explain why a large quartz like this can exhibit exceptional sparkle despite quartz having lower dispersion than many colored gemstones.

For buyers interested in complementary materials or for comparative reference, white opal is a hydrated form of silica that differs fundamentally from quartz in both structure and optical behavior, white opal displays a body tone classified as white, and its characteristic play of color is a diffraction phenomenon caused by submicron silica sphere packing, the regularity and size distribution of those spheres govern the wavelength distribution of the play of color, white opal typically has a lower hardness, around 5.5 to 6.5 on the Mohs scale, and a sensitivity to sudden temperature changes and dehydration, therefore white opal requires different handling and setting considerations than quartz, pairing a polished lemon quartz like this 82.19 carat oval with well selected white opal can create a striking contrast between controlled brilliance and opal fire, The Natural Gemstone Company presents this lemon quartz as an example of meticulous cutting and material selection, please contact The Natural Gemstone Company for additional images, orientation recommendations for setting, and advice on care, recommended cleaning for this quartz is warm soapy water and a soft brush, avoid prolonged exposure to heat and harsh chemicals to preserve the intense, natural color.