I know it won't help you with your Smith, but I had a similar problem with my 1911's.
I own 1911's in 3 different calibers (.45, 9mm and .38 Super) and wanted to differentiate the different caliber mags so I didn't, as an example, mistakenly grab a 9mm or .38 Super mag and put it into a .45 or vice versa. Wilson used to sell different colored base pads. Now, all of my .45 mags have standard black base pads, my Wilson .38 Super mags have blue base pads and I decided to go with Pachmyr 9mm mags (different look and a different base pad from the Wilson, so I ain't gonna confuse them anyhow) after I found a half dozen of them on sale for about $15 apiece.