Once mankind learns to produce gold, will people still wear gold jewelry?

No.. it would become like costume jewelry for children.

They absolutely still would. Just as they wear man-made diamonds and farmed like corn pearls. Yes, people pay hundreds, even thousands of dollars for pearls {especially Black Pearls} which are grown like corn on vines with rows and rows of oysters whose pearls are pre-programmed by adding a grain of plastic to the critter.

You see, and here’s where it gets interesting. I have this theory that human beings have a cellular memory system which allows us to access memories of our ancestors passed onto us via DNA.
One of our most basic memories appears to be what is precious to us. This is why precious metals and stones like diamonds and rubies and sapphires and torquoise etc… are so expensive and why we are willing to pay the rate.
we know that if the money system fails, we will be able to trade these precious stones and metals and jewelry for food and shelter and clean water and books etc…

I think they would. It would be cheap, and people already still wear jewelry made of cheap easily-manufactured substances like plastic.

What I would worry more about however, would be the immediate collapse of the world’s economy, which hinges on the value of gold.

Mankind has already produced gold in a particle accelerator.

Gold is an element. It would require a particle accelerator to make it as @SecondHandStoke said, and we’re only talking small amounts here. Unless that tech somehow drops considerably no one will be making gold anytime soon nor will it be cheap. Extracting gold from natural sources like the ocean is more likely but still less practical than gold ore.

The brokers of the gold markets would never allow it. They would choke the supply of gold to maintain it’s level of value.