Or you could beat all the carbon dating and that sort of thing by simply carving everything onto a slab of rock. Then you’d just have to be certain that it’s the right type of rock for that area.
Old stones are very difficult material since they have a patina. Oded Golan forged the Jehoash Inscription (http://www.religioustolerance.org/chr_joash.htm) stone tablet by first finding an old piece of stone and then engraving the text on it.
A piece of rock is constantly in a slow chemical reaction with the surrounding matter, usually air. This forms a thin but very hard layer to the surface of the rock called patina. Its height can be used to determine the age of the stone, a bit like the circles of a wood. So, using just any rock wouldn’t work, the stone would have to be from the right era. And the chemical contents of the patina also shows in which part of the world the patina was formed in, so the stone must be found from the right place as well.
The problem is, if you wish to engrave a writing to an old stone you are engraving through the old, genuine patina and exposing the stone under it. In order to fix the problem, you would have to create a fake patina to the bottom of the engraving marks.
This is very difficult. Oded Golan had exactly all the right materials, he made a fine powder of them and used hot water to make a paste out of them. The hot water caused the materials to attach to each other on a molecule level. He then put a thin layer of the paste to the engraved parts and used oven to harden the homemade patina.
However, there were two major problems:
1. The homemade patina was very soft. As you can imagine, mixing water and fine sand power doesn’t really create a very solid matter when the water is dried out. It can crack when you tap on it, while a real patina is very hard.
2. It’s possible to test in what temperature the patina was formed in. They tested the patina of the engraved areas and found out it had formed in temperatures of at least 40 degrees celsius. The temperature of which a real patina is formed usually matches the long term average temperature of the area, and as you can guess, there’s no place on earth where the long term average temperature would be over 40 degrees celsius.
So, don’t think about creating a fake stone tablet unless you have invented a way to fake patina