Contract Stone

Commonly used in Kraylin for negotiations, it is also found occasionally in other cities.
It is a gemstone which has been magicked in such a way that contracts made with it are hard to alter or duplicate.
As a contract is made, one of the two parties holds the stone and concentrates. The contract will appear on the stone as the party focuses. Once that is done, the first party then can focus and cause their seal to appear inside the stone.
The second party can then take the stone, look at it and be able to see the completed contract. Having done so, they can then impose their seal upon the contract shown in the gemstone.
Then by the words, "Contract stone, I invoke thee," the stone will start growing and once it has doubled in size it will split in two with a replica of the signed contract in either stone. Each party can then leave with a stone.
As a general theme, the stones usually start out blue or red. The blue ones will turn green once used and the red ones will turn yellow.