0.40 Ct. Blue Sapphire from Ceylon (Sri Lanka)

This 0.40 carat Ceylon blue sapphire presents a precise balance of size and proportion, measuring 5.06 by 4.10 by 2.52 millimeters in an oval outline. The cutter employed a mixed brilliant schema, combining a brilliant-style crown to enhance face-up scintillation with a modified pavilion geometry to retain color saturation through the depth of the stone. The measured depth of approximately 55 percent relative to the average diameter yields an optimized table-to-depth relationship that preserves a strong face-up presence while avoiding the dark windowing associated with overly shallow cuts. At the microscope and to the unaided eye the gem is transparent and graded as eye clean when evaluated at normal viewing distances, with an excellent polish that produces crisp facet junctions and tight light return. These physical metrics, together with precise facet alignment and a well-behaved girdle, create a gem that balances optical performance and wearability in standard jewelry settings.

Color is the defining attribute of this sapphire, described by its vivid color intensity and even distribution across the table and pavilion facets. The primary hue is pure blue with a slight tendency toward the cooler side of the blue family rather than strong violet overtones, producing a vivacious, saturated tone typical of fine Ceylon material. Pleochroic behavior is present, as expected in corundum, but it is subtle; the mixed brilliant cutting strategy reduces the appearance of directional color variation by averaging the two principal pleochroic axes through symmetric facet placement. Under diffused daylight the stone reads as a lively, saturated blue, while stronger artificial light emphasizes internal depth and localized flashes. The cut’s crown angle and table size were selected to yield a pleasing interplay between brilliance and body color: the crown facets act as efficient light collectors, while the pavilion facets return that light with minimal leakage, thereby reinforcing the vivid face-up appearance without darkening the stone’s center.

What gives this specimen an unmistakable signature are its internal features, in particular a delicate network of silk and discrete reflective crystals that combine to produce a distinctive, three-dimensional internal texture. The silk consists of fine rutile needle aggregates oriented along growth planes; these fine needles form a semi-continuous veil in localized zones, generating a softening of light that contributes to a velvety, saturated blue in the deeper areas of the pavilion. Scattered among the silk are pinpoints and isolated mineral crystals that produce micro-reflective points, which under magnification appear as tiny star-like flashes when the stone is moved. There are also a few small negative crystals and two-phase inclusions which, rather than detracting from the gem, act as optical anchors that break up broad flash and create dynamic scintillation. A handful of minute healed fissures exhibit internal reflectivity and subtle "feather" patterns; these healed features testify to natural growth and post-growth events and, in combination with the silk, fashion an inclusion fingerprint that gemmologists frequently associate with Ceylon provenance.

Heat treatment has been applied to this sapphire to optimize color and clarity, a standard and stable enhancement in the marketplace that has been executed to preserve the gem’s structural integrity while improving visual appeal. The heating process has partially annealed the rutile silk, reducing the density of needle aggregates in some areas and increasing transparency without eliminating the characteristic silk entirely. As a result, the stone retains its diagnostic internal texture while achieving an even, vivid color and an eye-clean appearance. The Natural Sapphire Company documents this enhancement and the Ceylon origin, and our cutting and finishing work emphasize both visual purity and diagnostic character. For design and setting considerations, the stone’s oval proportions and robust polish tolerate open settings that allow light entry from the pavilion, and the eye-clean nature ensures that the gem will present beautifully in solitaire, halo, or three-stone arrangements. Standard care involves avoiding sudden thermal shock and strong acids; routine cleaning with warm soapy water and a soft brush will maintain the polish and maximize the optical contribution of the internal silk and reflective inclusions that make this sapphire uniquely identifiable.