An open cluster of about 100 stars in the constellation Crux, also known as the Kappa Crucis Cluster after its most prominent member, a blue supergiant (visual magnitude 5.89, absolute magnitude -6.10, spectral type B5Ia). Located near Beta Crucis, the Jewel Box was discovered by Nicolas Lacaille when he was in South Africa in 1751-52. It is one of the youngest clusters known with an estimated age of less than 10 million years. Nearby lies the Coalsack.