20-Year Prospect
Humans have been obsessing over these sparkly little rocks since as early as the 4th century B.C. The question isn't whether or not we'll still be wanting them in the next twenty years—it's how much we'll be willing to pay.
The price of diamonds, and peoples' willingness to shell out several months' earnings for just one of them, depends on two things: the economy and marketing. If the economy's down, people will put food and clothing higher on their priority list than a flawless three-carat princess cut engagement ring, and gemologists everywhere will be feeling the squeeze.
The other thing that might make gemologists want to cry uncle? Viral videos that point out how the value of diamonds is completely fabricated. The diamond industry is basically owned by one company, DeBeers; it's been this way since 1888, when several hot South American diamond mines pooled their forces together to make diamonds kind of a big deal.
Since they've established a monopoly in the diamond biz, they're able to inflate the price of stones, making diamond rings cost quite a bit. If other companies were to cut in and start selling diamonds, too, the prices would plummet.
Ruh-roh.
The knowledge that the whole system is rigged is likely to make people mad. When you add in the fact that most consumers don't really want to buy blood diamonds, and the fact that synthetic diamonds are nearly indistinguishable from the real thing—which could drive the cost of "authentic" diamonds up to even more ridiculous prices—there's a chance that diamonds will begin to lose their sheen in the eyes of the public.
The moral of the story? Putting your future in diamonds isn't as secure as it sounds. Unless the economy crashes big-time, you should be able to do okay for the next twenty years, but becoming a gemologist isn't a golden ticket that will guarantee you'll never see hard times.