nope, no client mod that adds crafting recipes, items, blocks, or some other things work on servers. Your client has to communicate with the server while crafting, so your client will claim this makes a diamond, but the server will disagree. (Server is always right). Some mods though that do things that don't communicate with the server (like x-ray, or any mods that just add looks) work fine on servers.

ya

He Has a Testure pack It's Obsidian