Make diamond blocks immune to blue wither skulls

Diamonds are very hard. It would make sense to give them a very strong blast resistance (better than obsidian). Currently there are no placeable blocks immune to the wither blue skulls. It would be nice to have some available protection from the wither! Also, diamonds in general aren't as useful as they used to be before trading allowed buying diamond items in exchange for emeralds. Giving the diamond block a special use would give a reason to go mining for diamonds again.