When I bought my used 385XD, it had a blue trackpoint cover. It seemed "soft" and "deformable", so I was unsure: either cleaning it in alcohol chemically wrecked it, or it was a swap from a Toshiba or another laptop. I got a cap from one of those mice, and swapped
There was a blue cat's tongue trackpoint, but it only worked on some certain model of thinkpad, so the seller said (that alone is weird; usually all trackpoints are backwards compatible). If the trackpoint from the mouse worked on your thinkpad, then, I don't think you would have had one of those weird unique blue ones... that is, if what the seller was saying was true.
If your [strike]brick[/strike] 385XD, supports trackpoints made today, then it wouldn't have been the blue ones, by theory.