Marcel Tolkowsky (1899-1991) was a member of a Belgian family of diamond cutters and an engineer by education. He is generally acknowledged as the father of the modern round brilliant diamond cut. Developed by Marcel Tolkowsky in 1919, the "American Standard" (also known as the "American Ideal Cut", "Tolkowsky cut", and "Tolkowsky Brilliant") is the benchmark in North America. Wikipedia
The Gemological Institute of America, GIA, is the world's foremost authority in gemology, diamond grading, jewelry education, gemology research, diamond and gemstone grading reports and laboratory services. Gemological Institute of America : Gemology Rese www.gia.edu/research/1383/2280/article_detail.cfm
The definitive Wikipedia entry for Marcel Tolkowsky. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Marcel_Tolkowsky