Which property of opal can vary significantly among different specimens?

Opals are unique gemstones characterized by their distinctive play of color and various other properties that can significantly differ among specimens. One of the primary properties that varies is water content, which can range from 3% to 21%. This variance affects the stone's overall look and durability, with more hydrated opals often being more vibrant in color but also more susceptible to damage.

Moreover, color is another crucial characteristic of opal that can differ widely. Opals can be found in a vast spectrum of colors, including white, black, blue, and even transparent or translucent. The play of color within the stone, which is due to the internal structure of the silica spheres, adds even more complexity to its color characteristics.

Transparency also varies among opal specimens. Some opals are opaque, while others may be transparent or translucent, allowing light to pass through and thereby enhancing their overall appearance. The combination of these factors—water content, color, and transparency—demonstrates that all these properties can indeed vary significantly among different opal specimens, making it essential to evaluate each piece individually.