Catalytic Converter

I just changed my converter on my 02 Civic (LX), had P0420 code it was running fine after the change but the code is back and I noticed the converter has turned a different color. Is this normal or I’m should I replace it?

I just changed my converter on my 02 Civic (LX), had P0420 code it was running fine after the change but the code is back and I noticed the converter has turned a different color. Is this normal or I’m should I replace it?