Fire Opal engagement rings? Absolutely! Diamonds may be a girl's best friend, but Fire Opal engagement rings are a unique, original, and a far more affordable choice. This birthstone of October embodies the orange and red colors of a warming fire. The fiery sparkle of this gem makes a fire opal ring become the center of conversation Sapphire is the birthstone of September, and one of the most popular gemstones on the jewelry scene today. The deep blue color of a sapphire ring is just right for an evening out.