• If the bytecode of a contract exceeds 24KB then it is rejected by the Ethereum network.

• I wanted one storage space for all state variables

• one address from which I could design and implement all functions without bytecode size limitation.

• I wanted all functions to read and write to state variables directly, easily and in the same way.

• It would also be nice to have optional, seemless upgrade functionality

• to be able to replace functions, remove them and add new functionality without needing to redeploy everything.

• To be able to extend the smart contract system in a consistent, systematic way after it is deployed.

What is a Diamond

facet ?

Know these things to understand diamonds:

1. A diamond is a smart contract. Its Ethereum address is the single address that outside software uses to interact with it.
2. Internally a diamond uses a set of contracts called facets for its external functions.
3. All state variable storage data is stored in a diamond, not in its facets.
4. The external functions of facets can directly read and write data stored in a diamond. This makes facets easy to write and gas efficient.
5. A diamond is implemented as a fallback function that uses *delegatecall* to route external function calls to facets.
6. A diamond often doesn’t have any external functions of its own — it uses facets for external functions which read/write its data.

• Diamond - doesn’t have any external functions
• Facets - execute the read and write function of Diamond data.