Onyx engagement rings? Absolutely! Diamonds may be a girl's best friend, but Onyx engagement rings are a unique, original, and a far more affordable choice. Black and gold make a beautiful and elegant combination. A black onyx ring is a perfect accessory for any outfit. 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 Brown gemstones are gaining in popularity and smoky quartz is an affordable choice. A smoky quartz ring goes well with autumn colors and evening wear.