How do you know when a beardie is gravid??

How can you tell if a beardie is gravid? I have a couple of females that are getting very rotund.. They are housed with a male and I did catch him with one of the females several weeks ago.

I have heard it said that when near ready to lay the eggs, you can feel them inside the female somewhat like a bag full of marbles (but softer of course so don't squeeze them). I can only hope my pair will breed this year, if they have not already. If the female starts digging in the substrate a lot, it is probably very near time for her to lay and she should be provided a nest box in which there is enough sand to dig into to lay her eggs. Good luck.

In the later stages you can often see the eggs as the stomach will take on a very lumpy appearance. This is not always the case, such as with females who are somewhat heavy or are carrying a small clutch.
As Glen mentioned, digging is a good indicator. A female nearing time to lay will begin digging around in the corners of the cage, and be generally restless.
A laying box is very important or you risk egg binding. If you are never really sure whether she is gravid or not, I'd put a box in with her just to be safe.
I usually used something like a larger rubbermaid tub that was around 12" deep. I normally just used dampened soil, but sand would be fine too.
The female will excavate a burrow large enough to get her whole body into so choose a container of appropriate size.

Well I have noticed that they seem to put on weight.. but I do not feel any eggs in the belly.. belly does seem to be swollen. They are not very active right now at all they seem to be lying around. I guess we shall see what happens. Thanks again for the response.