What is the trade term for the vivid blue adularescence displayed by high-quality moonstone?

The vivid blue adularescence seen in high-quality moonstone is known as "blue sheen." Adularescence is the phenomenon where light is diffused beneath the surface of the stone, resulting in a glow or sheen that can appear to move as the stone is rotated. This particular effect is highly prized in moonstone, especially when it exhibits a strong, vibrant blue hue, which enhances its beauty and desirability.

This term specifically describes the optical effect unique to certain gemstones like moonstone, and it distinguishes these high-quality stones from others that may not display this characteristic as vividly. The quality of the adularescence in moonstone can vary significantly, so stones exhibiting strong blue sheen are often more sought after in the market.

Other options, while relevant to the gemstone trade, do not describe the specific optical effect associated with moonstone. For example, boulder opal refers to a type of opal that is found within ironstone boulders and does not relate to moonstone at all. Calibrated sizes refer to gemstones that are cut to specific measurements, and cabochon refers to a style of gemstone cutting, rather than an optical feature. Thus, blue sheen is the precise term for the vivid blue adularescence found in