As we all know, the epigraphs from Part Three are recordings left behind by ancient Radiants. Well...
I did some work on that.
Assuming that the gemstone that was used corresponds to the Order of the Radiant, here's the list of speakers:
Wait! There's more! Some of the gems were in the same drawers, and as such are numbered. Here's a compilation of these two cases:
Drawer 1-1, first, second and third zircon, Elsecaller:
Drawer 30-20, first, second, third, fourth, fifth and final AND a particularly small emerald, Truthwatcher:
I also mapped out the drawers and their gems, but found no pattern there.