Star sapphire, a variety of corundum that exhibits a unique asterism or star effect, is well-known among jewelry enthusiasts. However, if you're looking to expand your vocabulary or want to know more about star sapphire alternatives, there are a few synonyms to consider. One option is "star diopside," a green to brownish-black mineral that can also display a four-rayed star. Another is "star garnet," a deep red to purple mineral with a six-rayed star. Additionally, "star moonstone," a type of feldspar with a milky white appearance and blue sheen, can also display a star effect. Overall, while star sapphire may be the most famous star gemstone, these synonyms offer unique and interesting alternatives.