diamond, inclusions, gems

Gübelin reports electron-microprobe analyses of mineral inclusions from nine diamonds. The inclusions were studied either after crushing the host diamond and separating the enclosed mineral, or by cutting and polishing the diamond until an inclusion was exposed at the surface; separated inclusions could also be examined by X-ray methods. The analytical results are presented for the various inclusion minerals, with discussion of their significance for the origin and formation of their diamond hosts. Of particular interest is the identification of a red inclusion as corundum (ruby), the first substantiated occurrence of ruby as an inclusion in natural diamond; this ruby is assigned to the eclogitic suite of diamond inclusions. The paper contains 17 figures, 16 in color, and two tables.