I don't know what Colorado's knife laws are, but if there is a law against open carry, and if a cop can SEE your knife, ANY part of your knife, that cop might consider it to be "openly carried". And if you are arrested based on that cops opinion, then it will be up to the opinion of the prosecutor to decide if you should be prosecuted. And if you are prosecuted, then it would be up to the opinion of the jury whether or not the knife was being "openly carried". Bottom line is- there may be a lot of opinions involved in the matter, and those opinions can easily go against you.
However, if Colorado law specifies in detail what exactly constitutes an "openly carried" knife, then your description of carrying a pocket knife clipped to your pocket might not qualify as "openly carried" and you might be in the clear. But like I said, I don't know CO law.
Also, if there is case law (previous cases involving "openly carried" knives), then those cases can play a big role in determining whether or not your method of described carry does in fact constitute "open carry". But I don't know CO case law.