Application of rocking-scan method to detect the low-content diamonds in a complex mixture

A method for detecting large-size diamonds with low content in a complex mixture was described. Phase identification via conventional X-ray diffraction method is unsuitable because of the large-size and low-content characteristics of the diamonds. Thus, we proposed a convenient approach (i.e., rocking scan) for assessing the presence of low-content diamonds in a complex mixture. A thorough rocking scan of the (111), (220), and (311) planes revealed the presence of low-content diamonds prepared by reducing dense carbon dioxide with alkali metals. This procedure can be successfully applied to several standard mixture samples prepared by mixing α-SiO2, α-Al2O3, graphite, and pure diamond powders, which are commercially available. We estimated that the detection limit was at or below the 0.1 wt% level by using the proposed method under the current condition. This method is straightforward, routinized, and may be specifically developed to satisfy the requirements of public and private institutions for a rapid identification of other mixture phases, of which the large-size and low-content characteristics do not allow an instant phase identification by conventional X-ray diffraction methods. [Display omitted] •Rocking scan method is first presented for the identification of the large-size diamond with low content in a complex mixture.•We estimate that the detection limit is at or below the 0.1 wt.% level by the method under current condition.•The method is expected to be extended to other mixture phases with large-size and low-content characteristic.