Assaf is right in knowing that you are ahead when trying to validate an idea before just jumping in. In my experience, you should reach out to someone with experience in whatever field your idea should be. If it's more related to design of a physical product talking to an engineer would be helpful. If you have a business plan, you should find someone who has started some businesses. I would think that the worst thing you can do is find someone who will just tell you what you want to hear because they want your money. You'll need to find someone that you can trust. This would be someone who offers a fair rate and has experience in what they do. Do you have any more details on what you are looking for? I'll be happy to help you if I can!

I don't have that much experience in jewelry but I do have experience with 3D printers and prototyping. One of your best solutions is to use both. Using a strictly metal 3D printer would be so costly as to be prohibitive. However, there are 3D printers that can make castings. That way, you can customize the part exactly as you wish, 3D print it, then cast the part in any material you'd like. You would have a wide array of options without the high cost of going straight into 3D printing metal. Possible issues would come as casting with the 3D printed part might not be at the resolution that you need for delicate, precise jewelry. At that point, using a 3D printer would go back to just prototyping design then the casting would come once a final choice is made. If you have additional questions please feel free to contact me.

This is a great question. I understand that I am late in answering but I will do my best. In the business world you can never guarantee anything. In my experience there are two things you can do. One find a supplier/designer/manufacturer that you trust. One that wants to establish a good pipeline of potential customers and stealing ideas would detract business. This is a little harder and would require good research and maybe searching for designers that cost a little more. But it will be worth it in the long run if they are trustworthy. Two, create a non-disclosure agreement. This will allow that whatever you and the other party discuss is considered a private discussion and not a public disclosure. For the patent, this will allow your design to still be considered undisclosed and thus, still eligible for a patent. Hopefully, this will give you a strong start in your new product. Good luck! If you need any help in design or CAD modeling I would be happy to help, please know that I am available to assist and I have experience in this!