Eventually finished my UFO - a doily !  The coloured thread used is Lizbeth size 20 Jewels.  Am disappointed that it is out of shape.  It took me a while trying to pin it into shape but gave up half way.  It is very challenging tatting a doily as one never know how the finished piece will turn out.   I suppose it all boils down to tension.  Lesson learnt is never to put aside a tatted piece halfway but to try to complete the piece before embarking on another.