Diamond, Gold and Iron Blocks do not have a Stair and Slab variant while Copper Blocks do.
This inconsistency causes confusion, and lack of buildable materials to have parity with Copper Blocks.
Comments 2
Thank you for your report!
However, this issue is Invalid.
You have posted a feature request or a suggestion. This site is for bug reports only.
For suggestions, please visit Minecraft Suggestions on Reddit or visit the Feedback website.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
Feature request, not a bug.