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Diamond size frequency distribution (SFD) curves, combined with the associated dollar per carat per size class, play an important role in the diamond industry. Value per size class is unique for each deposit and typically varies from less than a dollar per carat to several thousands of dollars per carat for special stones. Recovery of large stone therefore contributes significantly to the bottom line of a large diamond producer. While the design of the process plant should prevent damage and possible breakage of large stones, it should also ensure adequate liberation of the finer diamonds. Innovative solutions are required to protect and recover type I and II diamonds if prominent within the resource. X-ray transmission (XRT) sorting presents the opportunity to develop flow sheet designs that incorporate a balance between exploitation of the resource and process efficiency, as well as practical capital and operating costs. This paper serves to illustrate the role and application of SFD curves in determining optimum cut-off and re-crush sizes within the flow sheet of a large diamond producer. A thorough understanding of the unique technical and economic aspects of a deposit provides the basis from where new and innovative technologies can be proposed, allowing mining companies to maintain and improve profit margins. It highlights the results of various plant trials and newly commissioned XRT sorters for larger size fractions. It also provides recommendations for future applications of XRT machines in the diamond process flow sheet.