Value Considerations, Color Play, and Authentication Advice in the Black Opal Ring Buying Guide One of the most valuable and sought-after stones in the world, black opals are renowned for their distinctive iridescence and color display. In addition, black opals have a long and illustrious history that dates back hundreds of years. For example, in ancient Rome, they were a sign of protection and mysticism; in other civilizations, they were linked to good fortune and nobility. Unbeknownst to you, black opals are more expensive than regular opals when set in rings and other gemstone jewelry. This blog post will discuss the factors that affect black opal ring value and go into detail on how to determine whether your ring is authentic.