If you upgrade the diamond armor to netherite while it has a netherite trim material on it then you can keep the netherite trim material completely on your netherite armor.
According to the Snapshot article it shouldn't be possible to put a material on the same material armor but with this bug you can.
In the attachments you can see the bug happening.
Steps to acquire netherite pattern on netherite armor:
Put diamond armor inside smithing table
Give it a pattern and use netherite material
Put the trimmed diamond armor back into smithing table
Upgrade the trimmed diamond armor to netherite
Enjoy the trimmed netherite armor with netherite material
Linked issues
is duplicated by 5
MC-259378
diamond trimmed with netherite can be upgraided to netherite
Resolved
MC-259379
Upgrading diamond armor with netherite trimmings causes netherite armor to have netherite trimmings
Resolved
MC-259384
Netherite Armor Trim on Netherite Armor
Resolved
MC-259460
About Armor
Resolved
MC-259465
Upgrading Diamond Armor with Netherite trim yields Netherite Armor with Netherite Trim
Resolved
Attachments
Comments 6
Can confirm this is a bug, but idk how it could be resolved... Honestly I vote for allowing trim to be applied to any armor regardless of whether it's the same material. I just tried using commands to give myself armor trimmed with its own material and it honestly does not look bad at all. Kinda cool actually.
I agree with you Conure, it does give a different pattern and I personally like it.
I do understand the developers limiting it though. It can be disappointing for some people for putting same material and then realizing it is barely visible.
I do hope this bug will stay around so that there is an actual possibility of doing it.
I also think they look quite good, tbh. It adds a bit more variety to the textures. Not sure how they'd fix that bug.
As of today's snapshot we can now apply the same material trim to the same armor! Thank you so much Mojang you guys are amazing
This is not a bug because the Smithing Template Netherite upgrade item is used to upgrade diamond armor to netherite armor