Saphire in crown. Case 25mm from side to side. 28mm lug end to lug end. Hinged back case.
Identification would be most appreciated.
EDIT: 2013.02.04 First digit of case serial number changed from 0 (zero) to 6, based on confirmation from Janet.
The 6 is a real puzzle. It is really the first time I see the combination of a "6" with the indication of "Bulova Quality, filled, American Standard" that is almost exclusively used in 1924 only. At least on the 15 or so models I have from that year. Prior and after 1924 the case inscriptions are different. The number stamped in a 1924 case would have been 13 or 15 or a 4 for 1924. The shape is that of a 153/154 model, the 153 being the gold filled version. But if the watch really is from 1926, then it would have had a name and not a number, IF advertized. But these roundish models, like the 156 and 158 were not advertized after 1924 i.e. might not have been very popular anymore. The movement seems to be from 1926. I have seen 10A's from 1926 so that matches. So the only scenario I can come up with is that they had cases (or only this case?) laying around from 1924, hence the above mentioned inscription, without a number. And they sold them out in 1926, stamping the number at the moment of final assembly on both case and the triangle on the movement. The dials came in either stripes or flowers. The ads always show flowers, but on eBay it is mostly the stripes being offered for sale. So, in conclusion: for me it is a "very special" 153.
In reply to The 6 is a real puzzle. It is by Alex
As noted elsewhere onsite, some time post-1924, the case serial numbers changed from the year being the second digit to it being the first.
This first number is often seen mis-stamped, giving an indication that it is done by hand. The last six digits would be stamped at the case factory, then on issue/delivery to the assembly factory/dept. the year stamp would be, well, 'stamped'.
This is not a fact, just my take after some time of looking into serial numbers.
This method changed again some time around 1935 to the sn being on the outside, and between 1932 and 1935, we often see two sets of case serial numbers, both inside and out.