Opal is the birthstone for the month of October. In the Zodiac, it corresponds with Aries, Scorpio, and Libra. Opal is also used as the gemstone gift for 18th wedding anniversaries. Like other special gemstones, Opal is associated with certain qualities. In this case, those qualities are hope, faith, and confidence. opal value Australian opal being the most sought-after origin draws a premium in the range of Rs 700 to Rs 5,000 per carat ($10 to $75 approx.). Being of slightly lower quality, Ethiopian opal price per carat ranges from Rs 500 to Rs 2,000 per carat ($8 to $30 approx.).