gems, garnet, grossular, hessonite, India, Orissa, Ghatpara, Dahikbala, Budhido, and Burubura

Hessonite garnets from the villages of Ghatpara, Dahikbala, Budhido, and Burubura in Orissa, India, are located in the high-grade metamorphic khondalite suite and occur either in calc-silicate lenses or in quartzite-amphibolite contact zones. The paragenesis of Orissa’s hessonite is linked to regional metamorphic processes, probably during Middle Proterozoic times. The colours of the stones range from pale yellowish and orange to brown, with refractive indices and densities for each locality as follows: Ghatpara: n = 1.738–1.752, D = 3.56–3.64 g/cm³; Dahikbala: n = 1.750–1.756, D = 3.58–3.64 g/cm³; Budhido: n = 1.751–1.758, D = 3.60–3.63 g/cm³; Burubura: n = 1.759–1.763, D = 3.60–3.66 g/cm³. In addition to calcium, aluminium, and silicon, chemical analyses reveal a distinct content of iron and traces of manganese and titanium. Microscopical study shows that the hessonite from Ghatpara is characterized by mineral inclusions, healing cracks with two- or three-phase inclusions, and growth marks which sometimes display strong interference colours under crossed polarizers. The inclusions in stones from Burubura are mainly healing cracks with two- or three-phase inclusions and growth marks. Budhido hessonite exhibits a strong oily appearance and mineral inclusions, while Dahikbala stones are marked by needle-like inclusions, growth marks, and some mineral inclusions.