Bartering items, whether they be cash, semi-precious/precious metals/gems, or expendable goods (food/ammo/medical/etc.) are ONLY worth what everyone AGREES they are worth. IF I had 100,000 rnds of 5.56, and someone wanted to trade me some gold for 1,000 of those rounds, then I have to DECIDE whether the gold is WORTH it to me. Can I feed gold to my "family"? Can I fire gold through a firearm? Can gold patch an injury/wound? What does it DO for me? The ONLY thing I could hope for is that someone, with something I WANT, finds that gold as important/precious as I did and VALUES it enough to trade for it.
In a WROL/End times scenario, would you rather take an ounce of some metal that you can't really do anything with? Or would you rather trade for Food/Medicine/tools/etc., something tangible/useful?
Where this REALLY gets interesting is ANYTHING that is a "crutch"/addictive. Coffee, Tobacco, Alcohol, etc. While I don't drink, I personally have a bunch of alcohol, in "Pint" +/- size bottles that easy to trade with/for (whiskey, tequila, rum, vodka). I also have a shit ton of coffee (instant and beans/grounds), to use for trade as well as my own habit.
I see "Money", paper currency and then "precious metals", only lasting/having value for so long after an event. People will probably keep hope that things will return to "Normal" for 3-6 weeks after an "Event". After that? ALL bets are off. Think of the movie "The Book of Eli", and how valuable potable water became.
I would ONLY invest/"hoard" precious metals AFTER I've got EVERYTHING else in place. How long, after an "event" would it take you to start gardening and harvest enough to feed you and yours? Then you need enough food to get you through to THAT point (2+/- years?). It's one thing to grow your own vegetables, but what about Rice and Grains? (you might want to store MORE than 2 years of rice and grains to supplement what you can grow0 Potatoes are a good filler and easy to grow/store. Then of course, there's meat/eggs/dairy. Beans are a good source of protein, but again how much can you STORE? Then you start looking at who in YOUR area MAY have meat/eggs/dairy to TRADE for.....and what will they TAKE in trade?
How much ammo will you "NEED"? How many firearms will you want/need? How much medical supplies will you want/need? What about CLOTHES? Shoes? SOCIKS (the forgotten item)? To you have EVERYTHING you'll need? Only THEN, after everything else you may want/need is accounted for, THEN you can start worrying about semi/precious metals/gems.
Now, having said all of that. IF I were going to gather precious metals for barter/trade in a WROL scenario? I would look at Gold and Silver chains, chains in which a I can cut links off, something like a "Curb" chain, with easily definable links that can be easily cut with a leatherman. I would look for 18K chains, from places like pawn shops. You don't care about the "Look/Style", just that they ARE gold/silver, and easily cut. What this all infers, is that you become REALLY good at identifying Gold and Silver, either through mechanical or chemical means. Your money would go a LOT further buying pawn chains than something like above, that is manufactured for the express purpose of praying on "fear".