A trilliant cut or trillion gemstone has which geometric shape?

The trilliant cut was introduced by the Asscher brothers in Amsterdam. In the early 1960s Leon Finker created his version on the "triangular brilliant cut diamond", which he called the trillion cut. Finker had a large diamond cutting factory in New York, and Henry Meyer Diamond Company, who was also cutting triangular brilliant diamonds, used the same diamond cutters, though their stones were cut slightly differently.