Hi Ivo and Rocco
Been upstairs to check now and the piece I have a vaguely similar finish on the pontil mark, was the huge vase I thought was Prachen originally but we now think it's possibly Kralik - Rocco, thanks for prompting me

I checked my other known Prachen vases and they both have polished pontil marks, so my memory is not good

and I guess there must have been different finishes on Prachen bases as yours are flat polished.
But I do have a very large thickwalled pale blue Chinese vase that has that pontil mark on the base Ivo.
m