Grandidierite

Refraction Fits

Cauchy approximation

Valid 0.38–0.78 µm

n

= 1.6050

V_{D}

= 65.0

n (λ) = 1.591 + 0.004872/ λ^{2}

Mg-Al borosilicate; rare blue-green gem. GIA dispersion 0.015. Source: GIA / Winchell / Liddicoat gemological tables.