At the end of Part 2 I showed that the cover branding arrived at by Columbia, around the spring of 1957, looked like this:
This very attractive branding was usually placed at the top right corner of the album cover. By the time stereophonic LPs were introduced by Columbia in September 1958, the arrangement had been modified slightly, with the "LP" component moved up and to the right of the Eye:
...a modification which enabled the trademarks to be displayed flush with the "stereo" indicator at the top of the cover:
(For monaural releases with a stereo counterpart, the trademarks were displayed at the bottom of the cover.)
This basic setup remained unchanged until about the summer of 1960, at which point, the trademarks lost their top-of-the-cover status on stereo issues, and they were reduced markedly in size:
The next major change to the trademarks occurred in the summer of 1961 - the "Lp" portion, presumably by then considered redundant, was dropped, and the Eye transformed into its final form with three concentric rings:
This branding lasted only a few months. By the end of 1961, new albums were featuring this greatly simplified configuration in the upper left part of the cover:
This basic design remained in use, with minor changes in typography and placement, through the late 1970s on Masterworks releases (the entire classical division of Columbia was rebranded "CBS Masterworks" around 1980), and continues in use to this day for Sony's Columbia popular releases. (Incidentally, ML 5746, a recital of French piano music by André Previn, was one of the last releases to be issued with the old "6-eyes" label - in the summer of 1962.)
So why did Columbia, having found a seemingly satisfactory formula for displaying its trademarks on album covers from 1957-60, feel the need for another change? A possible answer is hinted at in an article in the August 29, 1960, issue of Billboard Magazine headlined "Columbia, Philips in New Long-Term Pact Talks." It seems that Columbia had become dissatisfied with having Philips issue its product in Europe, and wanted its own label presence there, as RCA and Capitol already had. Since the Columbia name could not be used there, as EMI owned it, the proposed new label was to be known as "CBS Records." (Philips, for its part, did not relish the idea of giving up popular American product on its label, which is why Philips purchased Mercury Records in 1962.) My guess is that Columbia wanted to update its Eye trademark to fit a new international image. Certainly by the time CBS Records was launched in Europe in 1962, the Eye logo had assumed its new look and was being used to identify the new label.