I‘ve often wondered about the existence of fairs dedicated only to swapping, no buying or selling for money allowed. Seems to me that a fair for swapping would violate some basic rules of efficiency in economics. Swapping by it‘s very nature is difficult. Frank has vegetables to give and wants eggs. Alfredo wants the veggies, but only has jam to swap, no eggs. Carlos has eggs, but he wants sausages, no veggies or jam. And none of them have any idea at all how many eggs equal one big pumpkin.... It‘s difficult, and inefficient.
To solve this problem our ancestors thousands of years ago came up with a marvelous invention... called "money". Money was invented for the purpose of making swapping easier. Nevertheless, among many mineral collectors (luckily not a majority) the idea has somehow arisen that there is something shameful or dirty about using money to acquire minerals, and that swapping them is a somehow more "noble" activity. I don‘t understand it, but perhaps my 18 years living in the USA have polluted my brain with evil capitalist ideas

I predict that all fairs limited to swapping only will die, because it‘s just too much trouble, and there is constant downward pressure on quality as no one in their right mind wants a swapper to take his proustite in exchange for a calcite, so when the box of broken calcites comes down the aisle, the proustite disappears under the table.
As a dealer, I often get collectors coming to my table asking if I will exchange, and I usually decline. But there is one kind of swapper I do enjoy exchanging with and those are the ones who put prices on their labels! Then I know how much they value each of their stones, as they can see the same info on my labels. I pick the ones I like, and for which I agree with their value estimate, add up the total, and the swapping partner can then choose the same value from my table, and nobody says, "No, you can‘t trade for that piece", it goes strictly by the numbers. The process results in an equality of value information and expectations between both swapping partners.