See our: emerald jewelry.A composite stone (triplet) that is made in imitation of a natural emerald. It was originally composed of two layers of colourless quartz enclosing a layer of green gelatin, so that it appearedemerald-colour when viewed from above the top; but the gelatin was unstable and turned yellow, so this method was discontinued.The next type was composed of two layers of green quartz enclosing a slice of sintered glass, and later the two layers were made of colourless synthetic spinel (this being described as soudé surspinelle).Finally, the layers were made of slices of pale emerald of beryl, and these have been marketed under the trade-name of 'Smaryll'. All such imitations are detectable if immersed in water or certainother liquids, when the layers become visible if viewed from the side.