The type of necklace that Katherine is allowed to wear in Space Task Group is a strand of pearl necklace.
Step-by-step explanation:
Katherine, a popular character from Margot Lee Shetterly's work named 'Hidden Figures' is supposedly a mathematician working on a mission to launch one of her male colleagues into the orbit.
She is allowed to wear strand necklace in pearl which is made by stringing objects. This is the one that women used to wear in those days.