Once you've seen a ripe charentais, the color change will be obvious. It goes (almost instantly) from a gray-green to a light yellow color that might be called beige by some. What you call goldish is probably ripe and should be picked right away.

Also, you can smell the deliciousness when they're ripe.

Got a photo to post?

I've only grown charentais for a few years, but I'll lift each melon and if it's ripe, it starts to separate from the vine with almost no pulling or twisting effort. The unripe ones aren't that easy to remove, so I haven't picked any unripe fruit using this method.