you realise after a while that it just isn't important - its not the serial number that tells the buyer that its real silver - its the look, the feel, the weight, the sound.
i've got some really ugly silver - a 50oz bar, hand poured, air bubbles on the underside, no makers stamp, just a 99.9 and the weight stamped on it - i don't think i'll have much trouble selling when the price is as high as i think its going to get.