For someone who loves commerce as much as I do it is a little distasteful to tell you that there are four businesses that are not entirely honest. Three of the businesses are flat out dishonest.
The three businesses are: pearls, wigs and diamonds.
I went to a pearl wholesaler in Osaka, Japan and watched the entire process. I was a consultant for a minor issue at the pearl wholesale plant. Here is how the pearl plant works.
All of the pearls come in wet in netted boxes. They come in one door and are put on a conveyor belt. From there on they are sorted first by size, then by color and finally by surface quality. Almost all of the sorting is done by skilled women. In the end small boxes are packaged and shipped to the pearl distributors who put them in their final packaging form.
When the pearls end up in a retail location the price is determined entirely by the packaging. You can be getting a $400 pair of pearl earrings that are just as rare or just as common as the $50 single pearl necklace. You are paying for the box and the packaging.
Exactly the same thing is true for wigs that can run from $200 to $8000. The sewing and netting that hold the wig together may have a minor difference in quality worth several dollars but the final wig pricing is the result of packaging. There is no rarity or abundance of any of the particular hairs that are used. (Most wigs are sold to black women.)
The same is absolutely true of diamonds, but it is hard for people to believe this because they can get their diamonds appraised and be told that one diamond is $200 another is $12,000. It is usually the appraiser who seeks to satisfy the customer based on the quality of the diamond's setting not the diamond.
I learned this from my several department store clients. They never operated the pearl, wig or diamond departments. The boxes containing the products came into these departments with different pseudo-wholesale prices so that the selling staff would not know what was actually going on.
The department store would get private secret annual kickbacks from the wholesalers of these departments based on the level of success in selling the pseudo-high-end products.
The fourth product that is not entirely dishonest is gasoline. It is retailed at many different prices and occasionally some company claims to have a secret ingredient. In most of the United States the oil refineries are owned by entirely different companies than own the retail outlets. Trucks often have the names of the retail companies': Chevron, Shell etc. but the delivery trucks go to the closest refinery if their own brand name refinery is not available. Nearly all gasoline is the same regardless of the brand name at the retail outlet. You can check this yourself by looking at the number of oil refineries within a few hundred miles of your own gas station. There probably aren't many and there certainly aren't enough to match each one of the different retail brand names.
Over time and with the expansion of the Internet and Internet shopping I expect these pseudo-business distinctions to slowly disappear.