Dragons - Draconium Crystals
I just had an idea. This being an extention of draconic crystomancy (magical gemstone enhancement infusion), dragons can eat jewels if they're hungry enough. Like, their teeth are as hard as diamonds, but no-where near as brittle. So, it allows them to break gems.
However, just because they can eat gems, doesn't mean that it's a good idea to do so frequently. Dragons are considered obligate carnivores with very few exceptions.
However, when they do eat jewels, they act as a good source for minerals & it isn't unusual for there to be some left behind & not entirely digested because dragons aren't petravores by nature & thus, their bodies don't naturally digest everything in these gems.
However, their bodies do do something else. The minerals will sit in the stomach, for possibly years, &... cluster then form a new stone infused with the essence of the dragon it's inside of. Much like how oysters can form pearls.
Once it's grown to a good enough size, the dragon will then cough it up... much like a hairball.
On the plus side, these new stones are always spherical, ovular, or other rounded shapes, so that makes for an easier passage.
These Draconium Crystals are known for being both far stronger & far more valuable than typical earth-mined stones. They are also very beautiful.
They are also infused with a bit of the dragon's energy, thus making them ideal for use in crystomancy.
It should be noted that the stronger the dragon, the higher quality the stone. Not to mention that the older the dragon, the longer a stone takes to incubate, which gives results much like aging wine.
However, these stones are incredibly difficult to work with magically because, if you're not careful, the results could be deadly & explosive.
It takes an extremely skilled crystomancer with a deft hand & a keen mind to fully utilize these Draconium Crystals to their fullest.
Did I do this just to make dragons more cat-like?
Who can say?