Product Details

Blue Benitoite 0.28Ct. RARE Species: Benitoite (Barium Titanium Silicate) Chemical Formula: BaTiSi₃O₉ Crystal System: Hexagonal Weight: 0.28 Carat (notably large for gem-quality material) Color: Vivid sapphire-blue to slightly violetish blue Transparency: Transparent Luster: Vitreous to sub-adamantine Optical Properties: Refractive Index: ~1.76 – 1.80 Birefringence: Low (~0.046) Dispersion: Very high (~0.044) → exceptional fire Pleochroism: Weak (blue ↔ colorless) Physical Properties: Hardness: 6 – 6.5 Specific Gravity: ~3.6 – 3.7 Locality: Primarily from San Benito County (唯一 commercial source; now largely closed to regular mining) Diagnostic Features: Intense electric blue coloration rivaling fine sapphire Strong dispersion producing diamond-like fire Common triangular/trillion cutting to maximize brilliance Rarely exceeds 0.50 ct in clean faceted stones Gemological Notes: Benitoite is among the rarest gem minerals in the world and is the official state gem of California. Stones approaching or exceeding 0.25 ct in fine quality are considered significant due to the limited size of recovered crystals. The combination of vivid blue color and high dispersion gives benitoite a unique “neon-fire” appearance unmatched by most blue gemstones. Collector Insight: A 0.28 ct clean, well-cut specimen falls into the upper size bracket for benitoite, making it highly desirable for collectors and connoisseurs of rare gem species.