Can we have a recipe to upgrade the base items?

ie i find a Gold Kris with really good mods and i want to upgrade it to a platinum kris?

or maligaros from a deerskin to stealth gloves

I don't mind this idea, provided that the item is some sort of penalty. Maybe something like one less possible socket, or reduced damage/armor.

Not sure the items would need a penalty ... i mean D2 allowed tier upgrading, there was no penalties, and it worked fine. im sure its something GGG could consider. I also like the idea though for sure.

The thing is some of these uniques are meant to be just low level power boosts and are designed as such. Also uniques are not meant to be the best gear, some are but those tend to be very rare, but are meant to allow builds to be built around them.

Uniques should not be able to have themselves upgraded. That would be completely broken to turn a low level unique into some perfect weapon (imagine quill rain on max base bow?).

For rares it would be fine, maybe. If the item were rarer than a divine.