Chavet B210, c1980s (?)

The third Chavet B210 aka 153/6 (size number 6) in my cabinet.

There are very subtle differences between all three, but this one is the most different - primarily in the queens' crowns.  I have photographed the white queen from each of my sets for a side by side comparison.  The other two sets also both came in a box with Chavet branding, whereas this one came in an unmarked box - I *think* this might indicate an earlier production date.

In this set the white queen has 10 "scallops" and the brown has 11.  In my other two sets the queens have 12 and 13, and 13 and 11 respectively.  The small central finial is also of a different size across the three sets.  I'm pretty sure that I have seen a guide on this and how it changed over time, possibly by Animateur or Walterbiensur (on chess.com), though I couldn't find it whilst researching for this blurb!  If anyone has a link, I'd be really grateful to be sent it!