Opalescence is another characteristic that can influence classification. This phenomenon occurs when the opal exhibits a shifting play of color, often described as a "fire" effect. Opals with strong opalescence are typically more valuable, as they display a broader range of colors and a more dynamic visual experience.
In addition to these classifications, opals can also be categorized based on their origin. Australian opals are among the most famous, particularly those from regions such as Coober Pedy and Lightning Ridge. Other notable sources include Ethiopian opals, which are known for their unique color patterns and clarity, and Mexican opals, which often exhibit a distinctive orange or red hue.
In conclusion, the classification of opals is a multifaceted process that considers various physical attributes, including body tone, transparency, opalescence, and origin. Understanding these classifications not only enhances appreciation for these gemstones but also aids in making informed decisions for collectors and buyers in the market.