According to Baidu Aigou. com, black spinel is a kind of crystal-clear gem with unique color. Black spinel usually contains iron, chromium, titanium and other metal elements, and the existence of these elements will make the color of spinel darker. Black spinel, like diamond, has strong hardness and wear resistance, so it is often used to make jewelry. Generally speaking, the grade of black spinel is usually mid-range to high-grade, and the price is relatively high. Among them, the darker the color, the better the transparency, and the higher the value and grade of black spinel. Therefore, black spinel is divided into mid-range and high-grade, so it belongs to mid-range or high-grade.