Changing Fin Straps.

Is there a trick to changing fin straps? I have a pair of US Divers Blades and want to change the strap without destroying it. To put a long story short, I broke the buckle on my Blades, and got two new one's at a fantastic price except the new buckles are black and the straps they came with are grey. I know this sounds petty, but I just want to have black buckles with black straps. For those of you who are going top tell me I should use spring straps instead, I am well ahead of you - my jets have springs. My Blades are my old fins that I lend out to friends so I see no point installing expensive spring straps on them. Any suggestions? Thanks.