In this lesson, you will learn about asterism, the star effect found in certain gemstones. Tanja will explain that star rubies, star sapphires, and black star sapphires are some of the most commonly known materials with asterism. She demonstrates how to use a pen light to find the best angle to view the star in these stones, and what to look for when determining their quality.
The lesson also covers other materials that can have asterism, including moonstones, quartz, rose quartz, and garnet. Tanja will explain how asterism occurs due to specific inclusions within certain stones, and how they are cut to exhibit the star effect properly. She will also touch on man-made asterism, specifically the Lindy Star Sapphire, and how to tell if a stone is synthetic or natural.