Pulled deli ham from the fridge and noticed a rainbow-like shine on the slices. Is that normal?

this shimmer to be a sign of high-quality meat that has been sliced correctly.

While the iridescent shine is not a sign of spoilage, there are other visual indicators that can alert you to ham that has gone bad. Discoloration, such as a green, gray, or brownish tint, is a strong signal that the meat is no longer safe to eat. Mold growth, which can appear as fuzzy patches or spots, is another clear indication of spoilage.
Additionally, if the