Natural opals are graded based on their color vibrancy, clarity, brightness, and pattertain color pattrn. The best grade Natural opal gemstone, such as AAA Black Opal, Crystal Opal, and Harlequin Opal, display the most striking play-of-color and minimal inclusions. The rarity of ceerns, like rolling flash or pinfire, also determines their value. To invest in premium-grade opals, buy from Best Place to Buy Gemstones Online at GemstonesForSale, where you’ll find hand-selected, high-quality opals for jewelry and collectors.