Recently, a limestone box was discovered. This box is of the style known as an "Ossuary." This type of box was used by Jews between about 20 BC and 70 AD to store the bones of their deceased. There are many such boxed that have been found in varous archaeological digs. But this one has an inscription that translates "James, son of Joseph, brother of Jesus." If you are Christian or not, you can probably begin to appreciate the historic significance of this find.
But is it real? Forgery of archaeological artifacts, especially religious artifacts, is not uncommon today and it has been rampant historically. I'm told that if all of the bits and shards of wood believed to be part of Jesus' cross were gathered up, you's have enough wood to build a nice single-family house. Obviously, few if any of them are authentic. So, what about this box? Is it a fake from the middle-ages? It is a modern fake? Or is it real?
Limestone oxidized, it gets a patina, much like steel does. And by examining the patina on this box, experts have determined that the stone was cut approximately 2000 years ago.
That authenticates the box itself, but what about the inscription? Authentic and relatively insignificant ossuary boxes aren't uncommon and they generally don't bring very high prices for dealers either. So maybe some dishonest dealer hoping to make a lot of money took an authentic, but relatively worthless, ossuary box and added the inscription himself.
So, those same experts examined the patina on the inside of the inscription and determined that it is the same as that on the rest of the box. That proves that the letters were inscribed at about the same time the stone was cut.
This doesn't prove that the the James, Joseph, and Jesus mentioned are the Biblically-significant James, Joseph, and Jesus, but it certianly opens up that possibility.
It's a good thing that nobody cleaned that box up in order to "to see its true nature." It is that patina that reveals the true nature and helps to extablish the box's authenticity.