inclusions, gems

Gübelin discusses mineral inclusions in colored gemstones from the standpoint of their genesis and the information they provide about the geological environment in which their host crystals formed. He distinguishes inclusions according to their relationship to the growth history of the host—pre-existing minerals incorporated during growth, minerals formed contemporaneously with the host, and minerals produced by later alteration or exsolution. Particular attention is given to the morphology, orientation and mineralogical identity of inclusions and to mineral associations characteristic of different geological environments. Such inclusion assemblages can provide evidence for the conditions and sequence of gemstone formation and, in favorable cases, assist in determining geographic origin. The article represents Gübelin’s broader approach of treating inclusions not merely as identification features but as records of gemstone genesis.