If you've been in the hobby for any length of time, you're bound to have been asked this question. You've probably even asked it yourself at some point. It's a common query, and one that is surprisingly easy to answer given the amount of confusion it has generated over the years.
Simply put, if your Proud Arabian Mare is Glossy Alabaster, Glossy Bay (honey bay, not mahogany), Glossy Appaloosa, or Woodgrain, it's Old Mold. If it's any other color color, it's New Mold. Easy and straightforward, right? So why the confusion? And why are there old and new versions of the mold anyway?
In spring of 1957, the California pottery company Hagen-Renaker released their large Designers Workshop Arabian family sculpted by Maureen Love. By 1958, Breyer had released plastic copies of the mare and foal (with the stallion entering production in late 1958 or early 1959), but for the purpose of this post, we're only going to look at the mares. HR dubbed their mare "Zara," and Breyer named their mares Pride (alabaster), Sheba (bay), and Speck (appaloosa). (The Woodgrain PAM was never given a name.)
With that in mind, we know that the Glossy Alabaster color was available in 1958, and the Glossy Bays were in production no later than 1959, but the Glossy Appaloosa and Woodgrain colors were only produced for a short time in 1959, hence their far greater scarcity.
Lastly, most of the New Mold mares issued from the mid-1970s until the mold was discontinued in the mid-2000s have a bump on the back of their right front cannon bone. On some mares, it looks like the filling caused by a bowed tendon and on others, especially later mares, it's an obvious raised lump.