I have heard that there are at least 140 different styles of diamonds due to so many molds used and mold repairs changing the appearance of the diamond......that number alone is just with the single diamond ponies.
The diamond pony molds had lots of issues and were reworked numerous times. The lower part of the skirt was heavily reworked / replaced....you can see the horizontal seam line that goes through the diamond. Re-inscribing the lower part of the diamond after the skirt repair resulted in some crude funky diamonds. The middle insulator either has a 4 embossed on the rear skirt bottom, or that is from the mold that was later reworked yet again and had the number added