I have used Milliput Superfine to mend chips quite successfully. You have to knead together the two parts for ages to make sure it's all mixed and pliable, and you then have something that resembles plasticine that you can mould into shape. When it's dry and hard you can sand it into final shape then apply a bit of paint to match any pattern. I have then applied a cold glaze. When I first did them they looked really good and barely noticeable, however I have to say that although the glaze claims not to discolour, ones that I did some years ago have now yellowed a bit. Hope this helps you.
Phil
June 2009