That IS a nice one along with the neat insitus. Backlit does a nice job in the quartz inclusions. I wonder if the ancients actually sought out the prettiest looking stones even if other varieties were also in the area. ?
Here's a thought / experiment;
Hit your NWP collection with an ultra violet light ( in the dark natch )... IF they reflect a very visible distinct color, then try. . . >
Walk the beach in the dead of night with a ( cheap ) flashight style U/V light, the gemstones might show up like fireflies !