The Cat's Eye Emerald was a sizable, priceless gemstone of South American origin.
This little gem most likely originated in South America, where Catwoman gained possession of it. Although she claimed to have taken it fairly, the more likely reality is that she stole it, given the fact that she needed to smuggle it out of the country, and Batman wanted to stop her. After snatching the gemstone, Selina secreted it aboard an ocean liner, run by smuggler Enrique El Gancho, that set out from Buenos Aires. With a little help from Nightwing, she found out precisely when the ship would dock in Gotham, and tried to retrieve the stone. Luckily, he was able to subdue her in the end and get the emerald.