Career
She played in the first Women"s Chess Olympiad at Emmen 1957 – but had to withdraw after only two days upon learning her father had died. Heemskerk was awarded the Woman International Master (WIM) title in 1950, and the Woman Grandmaster (WGM) title in 1977. In January 1940 Heemskerk married FIDE Master Willem Koomen and soon gave birth to a daughter.
The marriage broke up in 1944.