19.24 Ct. Boulder Opal from Australia

This offering from The Natural Gemstone Company is a single, opaque Boulder Opal, presented in a freeform outline that accentuates its natural character, weight, and play of color. The specimen weighs 19.24 carats and measures 27.30 by 19.30 by 5.20 millimeters, dimensions that make it well suited to a variety of jewelry applications where a substantial opal presence is desired. The cutting approach is recorded as cut not applicable, reflecting the freeform shaping that follows the natural contours of the nodule rather than a standardized faceted or calibrated profile. Color is multi tonal and intense, exhibiting a vivid and lively play of reds, greens, and blues against a predominantly light to milky body, and the polish is recorded as excellent, lending a smooth luster and clarity to the surface that enhances the internal fire. There are visible areas of natural ironstone matrix typical of Boulder Opal, these darker brown inclusions provide a complementary contrast that highlights the opal color patches and contributes to the material stability and character.

In terms of gemological attributes and presentation, this Boulder Opal displays the classic intergrowth of precious opal and host rock, with the precious material forming zones of bright diffraction color across a stabilizing ironstone base. The intense color intensity means that under both diffuse and direct light the stone shows strong flashes and broad color patches rather than isolated pinfire. The freeform shape has been shaped and polished to preserve as much of the opal surface as possible, yielding an organic silhouette that maximizes color coverage while retaining sufficient ironstone backing for durability. There has been no enhancement of any kind, the piece is natural and untreated, and the polish quality affords excellent surface reflection without obscuring the internal play of color. The 19.24 carat weight and the moderate thickness of 5.20 millimeters provide a substantial face up area for impression and setting, while the overall proportions support designs where the opal is the central visual element.

Provenance and practical considerations for use and care are straightforward and consistent with Boulder Opal from Australian deposits. The origin is Australia, and the presence of ironstone matrix is characteristic of Boulder Opal from established Australian fields. The natural ironstone backing imparts additional toughness compared to thinner solid opals on a light ground, while still offering the vibrant color display that defines precious opal. Because this specimen is unenhanced, color stability is inherent to the material as formed, however normal precautions for opal care remain advisable. Avoid extreme or rapid temperature changes, prolonged exposure to chemicals, and high impact, and store the opal in a stable environment away from abrasive materials. For lapidaries and designers, the dimensions and freeform contours offer flexibility, as the stone can be set cabochon style in a bezel that follows the shape, or mounted in a custom setting that showcases the ironstone contrast. The Natural Gemstone Company provides this Boulder Opal with detailed measurements and condition notes to support informed selection and responsible design integration.