Don't be too sure just by the look. It can be deceiving, and the more modern light geen speck linen can look like Cortland.
The first two pictures are modern light green speck linen, not Cortland.
The third picture is Cortland.
In the fourth picture, the ebony cue (top) is the modern light green speck linen, and the rosewood cue (bottom) is Cortland.
Still think you can tell by the look? Also, I guess it's subjective, but to me, pressed Cortland feels smoother to me than other linen, but that can vary depending on technique and age.
Tim had some Cortland in the 1980s when he did some cues for me, and by the 1990s, he was using the more modern for my later cues. I'm not exactly sure when he ran out of Cortland, but I know his supply in the 80s was not very plentiful, as he showed me the only spool he had at the time. Though he could have attained more, I think the era of your cue gives you more of a hint as to whether it's Cortland, presuming it has the right look in the first place.