Which gem is capable of displaying three pleochroic colors?

Iolite is known for its unique pleochroism, which is the ability to show different colors when viewed from different angles. Specifically, iolite can display three distinct colors: violet, blue, and yellowish-brown. This distinctive characteristic is due to the gem's complex crystal structure and the way it interacts with polarized light, making it an interesting and valuable stone for both collectors and jewelers.

While sapphire and topaz may also exhibit pleochroism under certain conditions, they typically show only two colors. Garnet, on the other hand, generally does not exhibit pleochroism at all. Therefore, iolite stands out as the gem that can display a notable three pleochroic colors, showcasing the fascinating optical properties that certain gemstones can possess.