Reading 'The Origin Map' today - it has this table of star distances. I cross checked the distances on Wikipedia and there are large differences.I guess we have better measurements on the star distances than we did when the book was published (2002) - however even the estimated distances still have large margins of error (+/-| 10%).

It looks like Brophy took Vega as his reference (Vega's distance/speed is accurately known) and calculated the others based on this measurement.

With the large margins of| error, it's difficult to say whether the stones accurately represent the star distances, because there is no accuracy to begin with. I had assumed modern astronomy could tell the| distance of stars accurately - but without that data, I can't conclude if there is anything in this or not.