It has been suggested that are approximately only 1,300 Gem Black Opal engagement rings produced every year from Lightning Ridge. When you compare this to approximately 1.3 million diamond engagement rings produced annually! Natural Australian Gem black opal rings l is arguably the #1 Rarest Commercially Available Gemstone on Earth! Loose Opals hand-cut from the rough Opal are genuinely valuable and have a uniqueness that places them above every other gemstone.