This is a intermediate chapter on the interlock so I would not repeat information already mentioned millions of times on the internet: how the two "C"s interlock with each other. What I really wanted to point out is: 1). Not all CC hardware has the 3D interlock effect and that's totally fine; and 2). The CC logo has changed throughout history.
A lot of self-proclaimed authenticators, and many popular online authentication guides would identify the above Chanel two-tone interlocks in the banner image as fake, because the "CC" interlocks look weird. Do they look weird, or you have never seen them before?
Chanel bags from early 1980s to late 1990s are already hard to find. It takes a lot of experience to get to see these bags and once you have seen these exceptions, you will start to get a hang of it.
Some vintage Chanel bags, especially the ones made between 1980s and 1990s tend to have these “irregularities", say, the "CC" s are not in a perfect circle, the spacing of the "C" opening tends to be bigger. And these irregularities are consistent - from the CC turnlock, to CC interlock stitching, to zipper pull. When they all look a bit weird, they are real!