What are worthless gems?

Answer 1

Many gemstones, like diamonds are really worthless. Diamonds are one of the lamest gemstones in the world. At around 2000F, diamond turns into nothing but CO2 . Emeralds are also pretty much worthless. Beryllium Aluminum Silicate, that is. Beryllium is not extremely rare at all. In fact, beryllium is more than 10 times more abundant in the crust than bismuth, used in pepto-bismal!!. Rubies and sapphires are also very much worthless. They are really a crystal form of Aluminum Oxide/Silicate. Al2 O3 is very abundant. Zircon is another lame gemstone, although not as much. It is really Zirconium Silicate.

Now, about precious metals. Other than the traditional gold, platinum, and silver. There are also metals like ruthenium, rhodium, and palladium, that are also good for jewlery. Unbeknownst to the public, bronze is very cheap. That is what makes bronze the first useful metal.