Black Opals are powerful spiritual protectors. They repel negative energies and transform lower vibes into higher ones. As a result, Black Opals act as energetic shields. The Dark Opal body tone has a grounding effect on your aura. The cause of this dark body tone is from the fact that black opals have carbon and iron oxide trace elements present which causes an unusual darkness of the Opal and hence creates the colour to have an extra vibrancy to it. This vibrancy of colour makes black opal the most valuable form of all opals..