How do we sort sizes?

After the transition from the Dutch Guilder to the Euro many users found it difficult to distinguishing the news coins from each other. Was it only a matter of getting used to the new coins? Not quite, it still remains difficult to see at a glance which coins are in a wallet. When putting the old series (the guilder equivalent) of a dime, a cent, a quarter, a nickel, one guilder and two and a half guilder next to each other in a row beside the euro-series, the cause for confusion is clear. The difference in sizes in the new series is sometimes so small that only further studying of the lettering and color will identify the coin. The coins are no longer distinguishable at a single glance. This of course raises the question of which distinction we find significant. A better understanding of this can help us to also create more characteristic size differences in architecture – differences which create as much clarity as the differences between the old coins. 

(source: ir. D. Pouderoyen)