The bug
By placing the two nether gold ores aside from each other, the gilded blackstone used the old gold texture from the first texture from the nether gold ore when it came out. It doesn't seem to be that appealing when you find one of these in the nether like the new texture of the nether gold ore.
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I feel like it's intentional, like they found a way to rework and re-purpose the old texture without completely scrapping it.
I will agree with Orbic, though I will voice that it isn't the most flattering texture compared to Jappas other work. Perhaps a reworking of the texture is being created as we speak. Who knows.
Technically gilded blackstone is not a gold ore. It's just blackstone that is covered thinly with gold.

Well, yes, blackstone isn't an actual ore, but at least should appear sometimes naturally on Basalt Deltas or blacstone patches.
This seems like a feature request.