If you follow Greek mythology, then you know that onyx was first created from the fingernail clippings of Venus. Eros, being the trickster that he was, decided to give his mom’s nails a trim and then left the bits scattered around. The gods turned the nails into onyx stones.
This mystical birthstone for December and for the Zodiac sign Leo is actually silicon dioxide chalcedony quartz. When gas pockets form in lava, it gives the quartz an opportunity to fill the cavity. The igneous rock hardens and the quartz crystallizes. So, while the mythology is more interesting, black onyx jewelry did not originate with the fingernail clippings of a goddess.
Most of the stones found in jewelry probably came from deposits in Brazil. However, there are mines located across the globe including India and event he United States. California and Arizona have several mines.
Black onyx rings are commonly found in the women’s and men’s jewelry sections. It can be bold and masculine or mysteriously feminine depending on the setting.
The deep black abyss you see when you look into the stone is likely due to treatment. It is a common practice to dye or heat the stones to achieve the maximum depth of blackness. Polished to velvety sheen, black onyx jewelry is a mystery bordering on danger.