Which of the following is an effect commonly seen in gemstones like sunstone?

Aventurescence is a phenomenon commonly associated with sunstone, characterized by a shimmering or glimmering appearance that resembles the effect of tiny flecks of light sparkling across the surface of the stone. This effect is primarily due to the presence of inclusions, such as hematite or goethite, which reflect light in a way that creates this visual allure.

In the case of sunstone, aventurescence results from the scattering of light by these metallic inclusions, which can give the stone a captivating play of light and color, enhancing its natural beauty. This is a key aspect of sunstone that gemologists and enthusiasts look for when evaluating the quality and appeal of the stone.

Other phenomena listed, such as chatoyancy, which involves a narrow band of reflected light moving across the stone, or fluorescence, where a gemstone emits light when exposed to ultraviolet radiation, are not typically observed in sunstone. While parallax effect refers to the visual displacement of objects viewed from different angles, it is not relevant to the specific characteristics of gemstones like sunstone. Understanding these optical effects helps in identifying and appreciating the unique qualities of various gemstones.