0.87 Ct. Bluish Green Cabochon Sapphire from Montana

This transparent oval bluish green sapphire weighs 0.87 carat, and measures 7.12 x 5.82 x 2.11 mm, presented in a cabochon cut that emphasizes body color and internal characteristics, originating from Montana. The color is described as bluish green with an intense color intensity, and the clarity is graded as very slightly included when evaluated at eye level, indicating minor inclusions that do not materially detract from the gem when set. The piece has undergone heat treatment, a stable and well understood enhancement method used to improve tone and saturation, and it exhibits an excellent polish that maximizes surface luster and visual appeal. The Natural Sapphire Company presents this stone as a specialist offering for collectors and connoisseurs who value provenance and the natural character of Montana sapphires.

From an optical and gemological perspective this sapphire displays the expected properties of corundum, including a refractive index in the range of approximately 1.762 to 1.770, and a low birefringence around 0.008 to 0.010, resulting in minimal doubling of back facets in transparent material. The specific gravity of corundum typically falls between 3.95 and 4.03, providing a dense feel relative to many other gem species, and the hardness of 9 on the Mohs scale ensures excellent resistance to abrasion and suitability for everyday wear in most jewelry settings. The cabochon form alters the optical presentation, reducing facet derived brilliance while enhancing the perception of color depth and any subtle pleochroic effects, so that shifts between blue and green are visible as the stone is rotated under directional light. Internal features in Montana sapphires frequently include rutile inclusions, growth zoning, and small mineral crystals, and in this specimen the very slightly included clarity grade suggests small pinpoint or feather type inclusions that remain largely unobtrusive, while contributing to natural character and confirming that the material is natural corundum rather than synthetically grown.

The cabochon cut of this oval sapphire has been executed to preserve weight and optimize the interaction between dome profile and body color, with a dome height that balances saturation against face up spread, and with a symmetrical outline that will center easily in traditional settings. The excellent polish noted in the evaluation ensures that the cabochon exhibits strong reflected luster, improving apparent transparency and minimizing surface abrasion lines that can obscure color. For mounting considerations a bezel setting is recommended when the objective is to protect the cabochon while controlling the visible table area to enhance color saturation, whereas an open back or offset prong setting can be employed to allow more light to traverse the stone in applications where maximal transparency and light return are desired. Because the stone is heat treated, no special chemical or thermal sensitivities beyond those typical of corundum are expected, however prudent care during setting and repair is advised to avoid prolonged exposure to extreme temperatures or harsh chemicals that could affect mounting materials or surface polish.

Provenance and treatment transparency are central to The Natural Sapphire Company approach to sourcing and presentation, and this Montana sapphire is described with full disclosure of heat treatment and origin to inform specialist buyers. For long term care the consumer should clean the cabochon using warm soapy water and a soft brush or an ultrasonic bath when mounting hardware permits, avoiding steam cleaning when the stone is mounted in settings with tension or untested adhesives. The combination of intense bluish green color, cabochon silhouette, and excellent polish makes this 0.87 carat oval an attractive choice for collectors who value natural inclusions and regional character, and it offers versatility for bespoke settings that highlight color over brilliance. Please contact The Natural Sapphire Company for additional measurements, magnified inclusion images, or advice on setting options, and our gemologists will provide tailored guidance on how to showcase this Montana sapphire to best effect.