Application of Fibre Optics Reflectance Spectroscopy (FORS) for the determination of mineral pigments in jasper

In the accretionary Hellenides Orogen, gems occur in various rock types of mainly four tectonometamo

When it comes to the geographic origin of gems, curiously enough, historians sometimes put forward p

Gem-quality sapphires containing ‘exotic’ elements such as Sn, Nb, Zr, Ta, W, are of special int