Making Long Lasting Jewelry

Hi everyone, I have two questions regarding two different metals. First, I'd like to be able to start selling gold plated stainless steel jewelry, although I would like for it to last as long as possible. Is it possible to have gold plating thick enough to last an average jewelry piece's lifetime without fading, or would I have to go with gold filled in this case? How long would something like 5 microns last?

Second, what type of stainless steel should I be looking at for unplated pieces that I would like to last through everyday use (which would include some contact with water) without tarnishing or rusting? Would nickel free 316L stainless steel have any problem lasting through years of this type of use? I might be a bit unrealistic in my expectations, but I'd basically like to know how good the quality can get with fashion jewelry of this kind.

Why use stainless steel if you are going to plate it copper or brass would be much easier to work with, nothing that is plated is going to last an average lifetime especially rings, plating will wear off and become patchy and need to be replated, rhodium plated white gold typically only lasts twelve months,
300 series stainless steels all contain nickel, the only stainless steels that I am aware of that do not are F series used in surgical prosthetics,
What you are trying to to achieve has been has been solved thousands of years ago by using precious metals, just look at the Celtic Torcs etc. that have been unearthed in the UK, then go down to a harbour and have a look at the "stainless steel" on boats that is rusting from continual exposure to salt water, I know what I would use ( and do every day ) to make long lasting jewellery from.

P. S. I am not familiar enough with the legislation although there are strict rules on the use of nickle use in jewelley in Europe

I see, thank you for your reply! In terms of using precious metals, I intend to sell the jewelry, and I would like to keep it at an affordable price point (preferably under $100). I guess my question could be summed up as follows: how can I make the best quality jewelry I can make while keeping the price point under $100?

Price point and longevity don’t really work together in anything other than a precious metal. Price depends on design and materials. You don’t say what items of jewellery you would like to make at that price point. Say you were to make earrings in silver or small pendants you’d still be able to make small pieces under $100 but then I’m only guessing as I don’t know what you have in mind.
I think Bob is correct in saying that copper would be best plated but as you are in the US the laws on nickel don’t apply.
We mostly work in precious metals, some makers start off in copper, each have a different market

make stuff and see what people will pay for a price you are willing to sell at.

Your trading laws will need to be considered and possibly taxes. Each to their own really. Steel can be very nice in jewellery (jewelry) - it is one of the hardest to solder though, in my experience. You need to look at what medium you use to solder so that doesn't leave the customer reacting in a way that falls foul of the trading laws you work to.