Stepped And Split Brilliants

(via Diamond Cuts in Historic Jewelry:1381-1910) Herbert Tillander writes:

In diamond literature we often come across illustrations of a split-facet Brilliant, sometimes entitled the Lisbon Cut. The term has perhaps come from a Portuguese publication which has used it, like the term Brazilian Cut, to describe those fancy cuts so often applied when the cutter was aiming at retaining the greatest possible weight. Other terms are used as well: Max Bauer described it as ‘a Brilliant Cut with elongated facets’. Sperison (1961), and Hertz (1839) simply said ‘with a great number of facets’. Dr Kunz (1890) gave no description at all of this type of cut, not even with reference to the golden yellow Tiffany diamond.

As far as I can ascertain, no author seems to have realized that splitting facets lengthwise necessarily involves stepping. A facet edge can obviously not be applied to a flat surface, and the two sections of a bisected facet must always meet at an angle, no matter how blunt that angle may be. Watermeyer interprets this as ‘probably an attempt to flatten the very steep angles of these facets in an attempt to produce more light reflection from inside. This could be proof that certain cutters might have been aware of the prismatic effect of the cut diamond.