171.88 Ct. Blue Star Sapphire from Ceylon (Sri Lanka)

This exceptional gem offered by The Natural Sapphire Company is a finely balanced combination of size, provenance, and natural optical phenomena, presented with full GIA certification. The stone is a translucent, oval shape blue star sapphire weighing 171.88 carats, with exact dimensions of 31.48 x 25.59 x 19.76 mm. The cutting is a double cabochon, the clarity grade is very slightly included evaluated at eye level, the color intensity is described as intense, and the polish is excellent. There has been no enhancement to alter its natural state, and the origin is Ceylon Sri Lanka, a source historically prized for producing some of the most desirable blue corundum in the trade. The GIA report provides an independent assessment of these attributes, confirming weight, measurements, cut style, clarity description, lack of treatments, and geographic origin, which together form the foundation of the gem s market value and buyer confidence.

The double cabochon cut is central to the way this star sapphire reveals its most compelling optical qualities, because the cut is purposefully engineered to maximize asterism and controlled light return rather than faceted sparkle. A double cabochon has a gently domed top and a secondary curvature beneath that encourages internal reflection and concentrates the silk inclusions that produce the star. In a star sapphire the asterism arises from oriented microscopic rutile needles that intersect and reflect light as a coherent star, and the cutter s job is to orient the fiber layers parallel to the base so the star is centered and well defined. The oval outline and the 19.76 mm depth provide substantial volume so the star appears bold and mobile, while the excellent polish on the dome permits crisp contrast between the body color and the moving star. Because this sapphire is translucent and of intense blue color, light penetrates and scatters within the crystal, which deepens the perceived saturation and gives the star a floating, three dimensional quality. Under point light the star will appear sharp and centered, under diffuse light the asterism will soften and the gem will show a field of rich, even blue, a behavior that a discerning buyer will recognize as a hallmark of both skillful cutting and high quality material.

For the educated buyer these combined factors drive scarcity and long term value. Large, untreated star sapphires over one hundred carats are rare on the market, and provenance from Ceylon adds an additional premium because Sri Lankan material is renowned for achieving the ideal balance of tone and saturation in blue corundum. The very slightly included clarity grade means the stone is judged as eye cleaned with inclusions that do not interfere with appreciation of the asterism, while those inclusions are actually the very mechanism that creates the star, so their presence is integral to the gem s character and desirability. GIA certification reduces market risk by documenting the absence of heat or other enhancements, which is important because treatments can modify both color and asterism and therefore affect future resale and collectability. For use in jewelry the depth and size invite bespoke settings that protect the cabochon dome while allowing ample light interaction, typically a bezel setting with a high gallery or a secure custom mount that showcases the dome without subjecting the stone to impact. For collectors and investors the combination of scale, untreated origin, intense color, pronounced asterism, and authoritative documentation from GIA makes this blue star sapphire a rare offering. The Natural Sapphire Company stands behind the gem with provenance details, condition reporting, and guidance for mounting and care, and we recommend independent appraisal and appropriate insurance for purchasers seeking to include this extraordinary stone in a curated collection or to feature it in a signature commission.