Some women buy and sell jewelry . Some buy and keep jewelry for investment. They believe that the value of of jewelry overtime will grow faster than other types of investment. Both cases maybe correct. Both also could be wrong.

What will make it right or wrong is the personal financial situation of the investor . Buying and selling jewelry can be good business if you have a real market and know what items to sell . You should also know how to protect yourself from the risks of non payment, theft, swindlers and the like. 

On the other hand , if you invest in jewelry, and you do not have sufficient resources, you may just end up being forced to sell your jewelry at a loss when you need cash badly and you don't have any other asset except your jewelry.

The principle behind it is simple. The value of any asset depends upon what the owner can do with it.Ultimately, the disposition of any asset has to result in an increase in personal net worth.Otherwise, it is a liability.