There is never a catch all for Kate Spade bags since there are so many fakes.  However, here's a list of where they are made - which will hopefully help you identifying them.

USA, Italy, China, Taiwan, Dominican Republic (very limited production there), Indonesia, and the Phillipines. Most of the nylon bags were made in the USA until 2002, but now they are all made in China and Indonesia. All of the nylon accessories I have seen were all made in China. Most of the leather bags are made in Italy, and straw bags are typically made in Taiwan and the Phillipines.

Do Kate Spade bags have serial numbers?  Kate Spade bags frequently have small tags with production numbers. However, usually when a seller mentions the serial number, they are mistaking the patent number engraved on the magnetic snap closure for a serial number. Some sellers use this to trick you into thinking the bag is authentic; some sellers are just clueless about this fact. If you believe the bag is authentic, email the seller and ask if they're talking about the number on the snap - this is the patent number for the magnetic snap mechanism - or the production number. Many fakes have patent numbers engraved on the magnetic snap!

We only sell Authentic handbags from Our Store.  Thanks!