1.57 Ct. Cabochon White Opal from Australia

This listing describes a transparent 1.57 carat oval shape multi color White Opal, dimensions 8.91 x 7.23 x 4.80 mm, cabochon cut, clarity graded as very slightly included at eye level, light color intensity, excellent polish, no enhancement, origin Australia. The oval proportions yield a length to width ratio of approximately 1.23, creating a broad surface area for play of color while maintaining a substantial dome height that enhances depth and internal light interaction. The cabochon profile is intentionally high and symmetrical, with a centered apex and evenly graduated curvature from crown to girdle, which together maximize the angular range over which diffracted light can emerge. Transparency in a white opal is uncommon and technically significant, because increased light transmission through the body allows internal diffraction phenomena to be observed with stronger saturation and greater mobility than in more opaque material.

The optical behavior that produces the gems sparkle is rooted in the stone mineralogy and microstructure, specifically the ordered array of silica spheres within the opaline matrix. These spheres act as a three dimensional diffraction grating, and their size distribution and packing uniformity define which wavelengths are diffracted and with what intensity. In this specimen the sphere dimensions and ordering produce a broad spectrum response, yielding discrete flashes of red, green and blue across the surface as viewing and illumination angles change. The multi color effect is enhanced by the stones transparency, because transmitted light supports internal scattering and multiple internal reflections before exiting, increasing the effective path length for diffraction and intensifying color saturation. Observable pattern types include pinfire elements and localized broad flash zones, which coalesce under direct light to form lively moving color fields that are precise, crisp and spectrally broad compared with typical white opal.

The lapidary approach applied to this cabochon is focused on conserving material that contributes to play of color while producing an optical quality exterior. During preforming the orientation was established to expose the most continuous color zones along the long axis of the oval, minimizing material removal over critical color layers. The dome profile was developed using progressive wheels to produce a smooth, continuous curvature that avoids flat facets and allows incident light to engage the internal diffraction lattice across a wide range of incidence angles. Final polishing employed successively finer abrasives culminating in a neutral particle polishing medium to achieve an excellent polish with mirror like reflectivity, which improves contrast between the opal body and the diffracted colors. The very slightly included clarity grade denotes minute potch areas and isolated internal features that are visible at eye level under close observation, yet these inclusions are small and do not interrupt the continuity of color play or the stones optical performance.

For practical use and setting recommendations, the stones dome and modest dimensions make it well suited for classic bezel or half bezel settings that protect the girdle and maintain continuous viewer access to the broad color display, while also reducing exposure to mechanical shocks and contact with harsh chemicals. Given opal relative hardness and sensitivity to thermal shock and aggressive ultrasonic cleaning, routine care should avoid steam and ultrasonic devices and favor gentle warm soapy water and soft cloths. The absence of enhancements confirms natural hydration and original microstructure, which along with documented Australian origin provides provenance and lapidary integrity. This opal is offered by The Natural Gemstone Company, and its combination of transparent base, carefully controlled cabochon geometry, superior polish and naturally ordered silica sphere architecture is responsible for a sparkle that is technically distinct and visually unmatched among white opals.