kindly correct me as i might be misinformed. per my understanding, 5512 is indeed COSC all the while though "chronometer" is not stated on some early 5512 gilt dials but the chapter ring dictates the COSC specs. sale of 5512 did not take off due to its high price point in the past. there led to the rarity of 5512 n popularity of 5513.
You may very well be right. There are many theories and stories (?) or 'facts' about Rolex watches and the 5512 is no different. There are those who say that the 5512 have indeed from the start been COSC rated but the 4 liner came about to differentiate it from the 5513 which was introduced after the 5512. True or not? Who knows.
The other interesting thing about the 5512 is that early 5512 were fitted with caliber 1520 and 1530 which were not COSC rated. The thing is, some claim the early 5512 were even seen with caliber 1030 and we know that the caliber 1030 came both with and without COSC. As such, who is to say that the caliber 1520 and 1530 fitted in the early 5512 is not COSC.
Well some say that the 5512 were never fitted with the caliber 1520.
I do know that the COSC 5512 were fitted with caliber 1560 and 1570, which I believe were COSC rated caliber. I believe that these 5512 were the 4 liner 5512. If it is true the 5512 fitted with caliber 1560 were 4 liner 5512, than this would put to rest the theory that the 4 liner was introduced to differentiate it from the 5513. This is because the 5513 was introduced in 1964 while 5512 with the caliber 1560 were introduced circa 1961.
