The Jewel Box, Kappa Crucis Cluster, NGC 4755, is an open cluster in the constellation Crux, and was originally discovered by Nicolas Louis de Lacaille during 1751-1752. This famous cluster was later named the Jewel Box by Sir John Herschel when he described its telescopic appearance as "a casket of variously coloured precious stones." It is easily found to the naked-eye as a hazy star some 1.0° southeast of the 1st magnitude star Beta Crucis, and was given its name by its original Bayer star designation of Kappa Crucis. Since known as a star cluster, the second brightest cluster star, placed within the main A-shape, became known as Kappa Crucis (HIP 62931, HD 111973, HR 4890). This is a blue supergiant of spectral type: B3Iae, shining at the apparent visual magnitude of 5.94V. Two other cluster stars are brighter than κ Cru, namely, 5.77V magnitude star HIP 62894, placed at the tip of the A-shape, and HIP 62732 at 5.75V, which is 15 arc minutes closer to Beta Crucis / Mimosa.

This cluster is one of the youngest known, with an estimated age of 14 million years. It has an total integrated magnitude of 4.2, and is located 6,440 light years from Earth and contains around 100 stars.
(Wikipedia)