The printer only works with expensive, blue ink cartridges.
and
He found a tarnished, gold coin on the beach.
The printer only works with expensive, blue ink cartridges.
and
He found a tarnished, gold coin on the beach.
What is the state of the coin? Is it tarnished and gold (separate adjectives)? or is it tarnished gold (as a conjoined adjectival phrase defining a colour). Either would be acceptable.
But ... a tarnished, gold coin reads like the start of a list of adjectives where - erroneously - no third or following adjectives are given. An example might be ... a tarnished, gold and battered coin. From this viewpoint, the comma in the question is disruptive and unnecessary.
There is a relevant but long (not "relevant, long set") set of answers about the use of commas in listing in Should I put a comma before the last item in a list?