You know, even Moda has pictures on their site with the colors wrong. Case in point: I have a lot of their Marbles, but when I look at the actual fabrics next to one another, and then look at the colors on their site, well, I often have to tweak their pictures before putting them on my site.
'Cause I don't want anyone to be disappointed!
We also try to be careful, by looking at every bolt that comes in the door, and then looking at the picture we have (generally taken from the manufacturer's site) to be sure that it is accurate. Most of them are good, but I would say about 3% - 5% have to be re-pictured.
That said, computer monitors can display colors very differently!
So, if in doubt, go by the verbal description of a fabric.