dimonds
gems
All gemstones are not valuable. Many gems start from 0.20$ per carat too. Mostly all opaque stones are cheap in prices and transparent stones come high in prices.
rubies are the most valuable, but the shape and certain sizes can change the costs or the different gems if you got 1 kilo of each gem then diamonds are worth the most
Some stones are valuable. Most are not.
what properties do gems have that make them valuable
They are valuable because they are rare and take a long time to process to create a good looking stone. They are classified as "gemstones".
Twilight Gems: Assassins(10%) Twilight Stones: Dancers(10%)
The jewelry grade (white) diamond that is most valuable is identified as a D-colour stone. In fancy coloured stones, both blue and pink stones are valuable, although red might be the most rare, and therefore the most valuable. See the link, below.
cause gems can be made into money
Ruby, Emerald, Sapphire and Topaz.
Precious stones are called gems.
a crystal