1.57 Ct. Black Cabochon Star Sapphire from Ceylon (Sri Lanka)

This translucent oval cabochon is a beautiful 1.57 carat black star sapphire, measuring 6.94 x 5.56 x 4.00 mm, offered by The Natural Sapphire Company. Cut in a classic cabochon style to best reveal the phenomenon of asterism, this gem displays intense body color and an excellent polish. Its clarity is graded very slightly included, evaluated at eye level, a grade that for star sapphires is often an advantage rather than a detraction, because the fine rutile inclusions that create the star are precisely the silk that produces the optical effect. The stone is natural and untreated, no enhancement, and it comes from Ceylon, Sri Lanka, a source long renowned for sapphires with strong color and well defined stars. The cabochon proportions and a dome height of 4.00 mm work together to concentrate the reflected light, allowing the star to appear crisp and centered on the surface when illuminated properly. For an educated buyer, these documented parameters, combined with the untreated origin, provide the key facts that underpin both aesthetic appeal and market value.

The asterism on this specimen is a natural feature produced by oriented rutile needles within the corundum crystal, and the effect is a clear star like pattern that crosses the dome. Under a single overhead light source the star manifests as a set of narrow, star like rays meeting at a bright focal point, the rays showing a warm coppery bronze sheen against the deep, near black body color. The geometry of the star is created by three directions of needle like inclusions intersecting at 60 degree angles, which typically yields a six rayed star, and on this stone the rays are well defined, straight and show good contrast with the surrounding body color. Because the cabochon cut is symmetrical and well centered, the star moves smoothly across the surface as the stone is tilted, a characteristic known as asterism mobility that collectors and designers value because it demonstrates both internal structural regularity and superior cutting. The visual interplay between the intense body color and the metallic looking star gives the gem a dramatic presence that reads as elegant in a pendant, or bold as a ring focal point.

From a durability perspective this black star sapphire sits at nine on the Mohs scale of mineral hardness, a critical fact for buyers concerned with everyday wear. Corundum, the mineral family that includes sapphires and rubies, registers a hardness of nine, which is second only to diamond at ten, and substantially harder than many common jewelry gems such as topaz, quartz and the beryls. This hardness makes sapphire highly resistant to scratching in normal wear, and suitable for daily use in rings, pendants and bracelets, however toughness and resistance to chipping depend on cut and setting. The cabochon dome helps distribute impact forces across the curved surface, which tends to reduce the risk of surface abrasion, but the girdle and edges of a small oval can still be vulnerable to a sharp blow. For maximum long term protection we recommend a bezel or partial bezel setting that surrounds the girdle and secures the stone in a metal lip, alternatively a low profile prong setting with protective shoulders will reduce exposure. The gem is stable to household cleaning agents, and because this particular stone is untreated, routine care such as warm soapy water and a soft brush is appropriate, while aggressive treatment by steam or ultrasonic machines should be used with caution if there are any surface reaching fissures, and professional advice is advisable for any deep cleaning.

For the discerning buyer this 1.57 carat Ceylon black star sapphire represents an excellent balance of natural phenomena, documented origin and durable gemological properties, and these are the attributes that support both wearable beauty and lasting value. The untreated status and clear asterism, combined with the intense color and very slightly included clarity as seen at eye level, make this stone attractive to collectors who prize natural optical effects and to designers seeking a distinctive center stone that does not require enhancement. Its dimensions of 6.94 x 5.56 x 4.00 mm fit readily into a variety of custom mounting options, and its strong star will read well in pieces intended to be viewed from above, such as a bespoke ring or a refined pendant. If you would like a formal report or additional images showing the asterism under directional light, The Natural Sapphire Company can provide further documentation and personalized recommendations for mounting and care, ensuring the gem is matched with the setting that best preserves both its beauty and its value.