I agree fundamentally, but what Ive seen from looking at hundreds of documents over the last few years is that "selected" is used, though it is generally implied that these are the best of the best, most noteworthy, etc.
If youre buying a top notch uncirculated coin, you might classify it as "Select Brilliant Uncirculated" instead of "selected BU", though there surely are hundreds like it.
It seems that in general, "select" vs. "selected" also has some aspect of plurality to it... A "select" reference, or a "select BU" coin, etc. is a single item on its own laurels. "Selected" seems to imply the same, but multiple of same, still with the ultimate in quality or characteristic. A "hand selected" widget is an example of this implied quality, but I guess is more an indication of tense. The item if by itself, is implied to be "select", whereas the lot might still just be "hand selected" or "select hand selected". Very interesting to think about this...
Interesting thoughts... I may well read into the language completely wrong, assume that what is right is wrong, and should dock for using incorrect language