As Todd says, it really depends on the health of the anemone. Even an anemone in poor health can last a few weeks and then suddenly go poof.
Here in Japan, it is pretty easy these days to find a healthy gigantea (green, blue, purple, tan). Many are harvested relatively locally, and they are fairly common in the local trade. However, a healthy color haddoni is rather rare, especially as they don't tend to be found in such local waters. And people tend to buy these poor specimens anyway at the mad premium prices charged here (including myself early on).
My first carpet was a red haddoni that was not in the best shape. Needless to say, it didn't last very long. The only haddoni I managed to keep was a small blue-greyish one that wasn't spectacularly colored, but was in great health and locally caught. Learning firsthand what "CHEMICAL WARFARE" meant led to this anemone's demise, which was very sad.
In any case, color is pretty meaningless if it's not going to live more than a month. I've never been able to rehabilitate a haddoni in bad shape, but I'm sure there are people who can.
