Ad showing same image in admin's post as "engraved".
May 1922 ad, makes no mention of plain-cased octagon, only engraved, and both engraved and plain in the round cases.
These early cases seem to indicate the shape makes a difference to the gold content.
Later 1922/23 ads suggest this practice changed.
The date and prices are in line with those of the early Lady Maxims.
If we are thinking movement and dial replacement then I'm good with saying the case is Rubaiyat, but with Bulova on the dial I would still go with Lady Maxim.
We have a number of Rubaiyat watches marked according on the dial or not marked at all, and a 1923 movement with a Bulova stamped dial in a Rubaiyat presents a problem for me.
In reply to Just wondering why you say it by bobbee
In reviewing my earlier comment and looking at some old threads it indeed does look like Bulova were stamping their movements with 'Bulova W Co.' whilst still trading as 'J Bulova Co.'
So it would seem acceptable that a 1922 watch have a movement stamped with 'Bulova W Co.'
In reply to Another Rubaiyat plain-cased by bobbee