This is a 8mm Barion cut Sapphire, ( 2 carat parti ). The stone is a yellow, blue combination that shows blue, green, or blue, depending on the angle you view it from. It is ready to set in your choice of jewelry. Parti sapphires (also known as polychrome sapphires) are a rare type of corundum gemstone that cannot be be replicated in the lab. ... They are an incredibly hard and durable gemstone. Only diamonds and moissanite are more durable.