Probably the largest faceted LYSO in existence and certainly the only one in a complex precision cut 97 facet Portuguese. Lyso is a lab grown scintillation crystal, widely used in PET scanners and for detecting gamma rays, x-rays, and gamma particles. Energy absorbed is converted to a phenomeonal blue glow that radiates, even natural sunlight will cause a color change; photo shows the intensity in shortwave UV. Would make a nice gem blue battery display for a radioactive collection, lyso is in itself weakly radioactive from lutetium decay and this gem will glow on its own from its own lutetium decay. Lyso is rarely offered for sale as gemstones, because of its lower hardness of 5.8 and the difficulty of sourcing commercially available rough. When offered as faceted gems, stones are typically under 5 cts. Sourcing the rough to create a 60.6 ct Portuguese was extremely difficult. The table shows minor directional pitting from crystallographic strains during crystal growth on such a large specimen. 
19.98 mm in diameter and 11 mm in height from the top of the table to the culet.