6.13 Ct. Greyish Blue Cabochon Star Sapphire from Ceylon (Sri Lanka)

This oval cabochon star sapphire weighs 6.13 carats, and measures 11.25 by 8.94 by 5.75 millimeters, and it is presented in a classic translucent greyish blue tone with a light color intensity, and an excellent polish. The cutting style is cabochon, and the stone displays a symmetry and dome height chosen to maximize asterism, the phenomenon that gives star sapphires their distinctive appeal. Clarity is graded as slightly included when evaluated at eye level, and this gem has no enhancement, natural provenance, originating from Ceylon Sri Lanka, a source historically prized for fine star sapphires. The Natural Sapphire Company is presenting this specimen as an unheated, naturally occurring star sapphire, a characteristic that matters to collectors and discerning buyers who prioritize natural state and provenance.

The natural asterism in this sapphire is caused by oriented networks of fine needle like inclusions, most commonly rutile, that intersect beneath the cabochon dome to form a well defined six ray star that glides across the surface as the light source moves. Under direct light the star sharpens to a bright central point from which the star like rays extend across the dome, and under softer or ambient light the star softens into a luminous starburst that reveals subtle banding and growth zoning within the crystal. The slightly included clarity grade contributes directly to this signature, because the density and orientation of the internal silk and minute reflective platelets enhance the visibility and contrast of the star rather than diminishing it, creating a unique internal fingerprint. You will also notice small warm toned mineral deposits that sit slightly below the surface, these natural features add character and proof of origin, and they help to localize and accentuate the star in certain lighting angles.

For the educated buyer this sapphire presents a compelling combination of attributes, namely its Ceylon origin, unenhanced state, aesthetically pleasing greyish blue tone, and a robust six ray asterism that is practical for use in high end jewelry. A 6.13 carat cabochon at these proportions is substantial enough to be the centerpiece of a bespoke ring or pendant, and the excellent polish and carefully proportioned dome ensure the star reads well when set. Slight inclusions are typical and expected in natural star sapphires, they are responsible for the optical phenomenon, and when evaluated against the whole stone they do not compromise structural integrity, given corundum hardness and toughness. Collectors value unheated stones from Sri Lanka for their traditional character and for the predictable stability of their light color intensity, and lapidaries and designers will appreciate the centered asterism which simplifies orientation when setting the gem. Please contact The Natural Sapphire Company to view this gem in person or to discuss setting options, and we are happy to provide additional photographs or viewing guidance to help you assess the star under different lighting conditions.