i have one of the ceramic pencils too- my is a dritz instead of sewline- but uses the same leads- in fact my refill lead is sewline for my dritz pencil. i too love it = a nice fine point- shows up well- i marked a whole queen size quilt with the green lead- (white whole cloth quilt) and have had no problems removing marks. i used to use chalk most of the time- but i love these much more.
i purchased my pencil at Joannes ($14 & change) i bought refill leads at my lqs.