Not too sure but first you'd need money to start. Then you would have to get your gold and diamonds from a supplier. After that you would need it refined and made into jewerly designs by a desinger. Then you can sell it to put you in the positive of those expense.
p.s. probably not a good time to start a jewerly store with the economy as it is.
p.s.s You should invest in stocks while you do this because if stocks are down gold goes up (which you will have in physical possusion) and vise versa so you will awaly have a fallback for either one.
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