Nyx is the daughter of Chaos and was considered as the first child making her the first deity to exist assuming the role of a creator. She was born at a time where the world didn't really exist and had 4 siblings, Erobus, Gaia and Tartarus although in different versions, Tartarus and Gaia are not considered as her siblings or the children of Chaos.
Nyx in literal form is described as the night that surrounds us whereas in her physical form she is shown as a very beautiful woman in black, surrounded by dark mists or a winged goddess.
Since Erobus and Nyx were the two oldest Primordial deities, the world was in complete darkness as Erobus, himself was the God of Shadows and Darkness while Nyx, Goddess of Night. However, this changed as both Erobus and Nyx gave birth to Aether (Light) and Hemera (Day), the exact opposite of their parents.
Nyx has had many off springs including twins, Thanatos (God of Death) and Hypnos (God of sleep and dreams), Mockery and Woe, Eris (Goddess of Strife), Moirai (the Goddesses of Fates: Clotho, Lachesis and Atropos), Nemesis (Goddess of Retribution) and many more.
Nyx lived in Tartarus, a place of torment, suffering, and darkness. During the night, she and Erobus would emerge hand-in-hand as they blocked the light by Aether, bringing darkness and night. Hemera being the opposite of Nyx, would emerge from Tartarus bringing day leaving her parents behind and would return when it was Nyx's turn. Both Nyx and Hemera never got time to spend with each other as they never were in the same place. This story best explained the formation of Day and Night in Greek Mythology.
Nyx may not be seen as the center in many mythical tales, but it is said that she was the most powerful and feared among many Gods including Zeus. Once, Hera (Goddess of Birth and Marriages) asked Nyx's son Hypnos to put Zeus to sleep as Hera was trying to plot against him. However, the plan failed as Zeus found out about it and chased Hypnos. Nyx gave her son protection in one of her caves. Since Zeus was scared of Nyx and did not want her to be angered, he returned home.
This shows how feared, strong and influential she was as a deity. Although she is the Goddess of Night, she is exactly the opposite of evil. She never did anything evil compared to Zeus who in multiple occasions has committed things unnecessarily. By many she is seen as a villain due to her dark and mysterious nature. She was only worshiped as a background deity.
The moonstone is used to honor her as It reflects it’s owner and is only to be used during the full moon. Nyx is among the first creations before there was anything. She brought Night to this world and came along with it. Her existence and importance is mentioned in many Greek poems and is symbolized as a star or a moon.