In the world of bonds, there are several different categories that an investor might consider: Corporate, or sometimes called investment grade, have the best ratings for safety and security, but the returns are quite low these days. Then there are municipal bonds which cities and states issue to help them build and make infrastructure improvements. These also offer a paltry return in the current low interest environment, as well as the increasing risk of cities and towns defaulting on their promises to repay.
Then there are high-yield bonds, otherwise known as junk. These are the bonds that pay a higher rate of return because the companies that they back are riskier bets and must pay a much higher premium to borrow the funds. Because they pay a higher interest rate, the holders of the bonds get a much higher rate of return on the bonds. But the risk of default grows as well.
How do you visually illustrate the concept? I was drawn to images of shiny metallic coins, newly minted gold and silver, stacked in neat piles. Then I started thinking about my junk drawer in the basement, a collection of extra hardware left over from various projects. Why not juxtapose? The resulting image works to sell the idea.