I don't know how anyone is going to know where the original one came from 15 years ago if you don't, but you could at least measure what you have so you get the same size. Even if you did buy from the original vendor the colors they offer might not be the same anymore. You might have to replace all of them to get them to match.

If you're really lucky then the supplies haven't changed in 15 years but I'm going to guess they have.

I'd go to any local or regional building supplies companies to see if they can match it because they probably supplied your build. That's your only chance.

Wouldn’t you say this is an oil rubbed copper? All the new oil rubbed copper balusters have just one long streak of copper…As opposed to an aged look.

spray paint