Gold has some disadvantages, as I see it.
SHTF scenario -The downside- You - "I want to buy that (insert desired object or sevice), I have this gold coin". Him_ "how do I know it's gold?" "how do I know it's pure?" and most important-"how do I know what it's value is? The answer is , of course, he will not know , so, in order to cover his ass while dealing with an unknown quanity, he will offer far less than what your expected valuation is. And this is going to be worse in this country than say, in India or some other place people are used to trading in gold. You may very well find yourself trading a Krugerand for a pack of cigarettes. Gold has no intrinsic value, except as a metalugical component. Same is true of gems.
A truly high value, extremely lightweight , totally transferable liquid item ?-- maybe knowledge. It can never be taken from you and is totally invisable. What is the value of a Doctor, mechanic, carpenter or gunsmith when the SHTF?
Commodity's are a definite, but they are bulky. Cigarettes, coffee, booze, all will retain value just fine. But how do you carry? The downside here is the value is enhanced in the stricken area, in the calm area it will decline.
So I guess the question is really, what do you want from the "wealth stash". Is it a trading item that continues to have value in the disaster, or is it a fund to be converted back into currency when you get to civilization?