I've started a binder just for my Diamond Kings cards.
I confess that at first I looked at these insert cards with not that good appreciation. But thank goodness we sometimes get to some cards and start seeing them in a complete new light!
I like black borders and in '87 Donruss did a fair good job with it. And the DK cards are looking great! Even more than the base cards.
I know that they are not that centered (Just look at the Joyner one...) but wax era is that. And much more!
Other think that made me start liking these cards is the card back with so much trivia! I'm more into trivia info than stats.
