I recently cut a 14×10 pear shaped Topaz using one of the Long designs. The pavilion on this design to had an offset and a keel that prevented using the standard cone dop. I ended up doing the same modifying a cone with a vee section. A standard vee Dop would have worked but I felt I needed a little more support the cone section of the modified Dop provided. I have never seen a standard produced vee-coned dop.
The Gem Garden
San Marcos CA