Final answer:
Asterism is not a result of the alexandrite effect. The alexandrite effect refers to the color change seen in the gemstone alexandrite under different lighting conditions, while asterism is the star-shaped pattern seen on some gemstones and is not related to this effect.
Step-by-step explanation:
When discussing the alexandrite effect, this refers to the phenomenal color change that occurs in the gemstone alexandrite when it is viewed under different lighting conditions, such as daylight and incandescent light. The options given regarding the alexandrite effect are:
Color change in different lighting
Pleochroism
Asterism
Chatoyancy
Color change is indeed the defining characteristic of the alexandrite effect, where the gemstone changes from a green or blue-green color in daylight to a red or purplish-red under incandescent light. Pleochroism is another phenomenon that can be observed in alexandrite, exhibiting different colors when viewed at different angles. However, asterism, which is the appearance of a star-shaped pattern on the surface of the gemstone, and chatoyancy, which is the 'cat's eye' effect seen in some gemstones, are not related to the alexandrite effect. Therefore, the correct answer is that asterism is not a result of the alexandrite effect.