Thought I'd go through the 80s catalogs and I found a page in the 1983 gifts and accessories catalog.
See picture with details here:
S&W Tie Tacs - Available in a wide variety of styles including miniature replicas of handguns, handcuffs or S&W Logos.
Product No. Description
W. 150000406 Model 19, Platinum rhodium plating
X. 150000405 Model 36, nickel plate finish
Y. 150000404 Model 39, Platinum rhodium plating
Z. 150000408 S&W logo, 14k gold and German silver
XX. 150000401 Model 19, Gold electroplate finish
YY. 150000409 S&W logo, cloisonne
ZZ. 150000407 Handcuffs, nickel plate finish
150000608 S&W logo, gun metal (not shown)
1500006 10 "First Issue", nickel plate finish (not shown)
150000613 L.Frame, gold electroplate finish (not shown)
So the 3 pictured are X. XX. & ZZ. S&W pins.