一般有六種:綠碳化硅、白剛玉、棕剛玉、碳化硼、紅寶石(又名燒結剛玉)和天然玉。百度百科:http://baike.baidu.com/link?url=yX5jeETlJwYagLU4-xXAJMflHxLYzYsNRktL8Ws7DyQc5XXpXRzBsuF5JyBi-lvJ_0LNxr0qbbkMp38vBRizwK