I looked at the image you used in your other post and that blue chair is without a doubt a knockoff. For one thing the base of a real ball chair is always painted to match the actual chair itself and would never be left unfinished as the one in your photo is. If the chair looks old and shows wear then it is probably an Asko production piece as these were not reproduced until recently. Also Asko branded their name into the bottom front of the chair itself. If the chair looks new you could have a knockoff or a recent real Adelta version. Adelta will place a sticker on the base but sometimes this is removed. Your best bet is to look at the quality of the piece... if the sticker is not present you might want to avoid the item and if the base is left unpainted you should run away from it as fast as you can.
Yeah i know the picture of the chair i put up wasnt real babes i was just sayin that i liked the chair in those colours. I have now got a original ball chair but want another one