Agate is a natural semiprecious gemstone. Black agate is sometimes referred to as black onyx. The highest quality agate is mined in Brazil which is why Shane Co. sources the majority of its gemstones from there. Agate measures 6-7½ on the Mohs scale
and is very robust. It can be polished to a high shine, which is why it’s an excellent choice for any woman’s jewelry wardrobe. To keep it in tiptop condition, black agate should be cleaned with a soft cloth and warm, soapy water.