Thanks for including my Engraved Busks in this interesting article about the evolution of busks :) Just a little add on to clarify, the coloured engravings aren't actually filled with anything. I use a colour annealing process (which is basically heating up the metal to specific temperatures using laser engraving equipment). So, as there's nothing added to the loop to create the affect, the colour can't be chipped or wear off - it's permanent forever!
Thank you for the very informative article. I have not seen the different colored busks. I will be on the lookout. Thank you also for not only informing about the new type of bones, but sharing where they can be purchased.