beryl, synthetic beryl, emerald, synthetic corundum, gems

Gübelin reviews the diagnostic properties of several recently introduced synthetic gemstones and the problems they pose for separation from their natural counterparts. Emphasis is placed on the combination of conventional gemological properties with microscopic examination of inclusions and growth structures, supplemented where necessary by spectroscopic and other analytical methods. The article discusses characteristic features of newer synthetic materials, particularly synthetic corundum and emerald, and shows that physical constants alone may be insufficient for identification as manufacturing techniques increasingly reproduce the appearance and properties of natural stones. Gübelin stresses the diagnostic importance of flux residues, metallic inclusions, growth zoning and other internal features associated with particular synthesis processes. The paper summarizes practical criteria by which these newer products can be recognized in gemological testing.