Tulip stool with unusual colour base.  

Hi,
I'm sorry it's another Tulip thread - I've read through the many others to try find an answer!!!
I just picked this up and was wondering if any of you had seen this type of finish on the underside of the base before? I don't know if it's a Knoll stool, there aren't any identifying marks on the base as you can see. There may have been a label on the black fabric but all that remains are the staples. I'm in the UK, but I'm sure it's not an Arkana stool as these are pretty much always stamped.
Your input would be much appreciated!
ps. Note to self: must hoover floor before taking close up pics!!!!!
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