Pretty simple in photoshop.
1. Photo a blank chip/solid.
2. Select just the chip, duplicate the layer and desaturate to just grey.
3. Put your chip image/inlay images between, I just draw out the spots and select colors that are close to real life.
4. Play with the overlay settings on the grey mold layer. I usually go with linear light at ~50% opacity. For inlays I might reduce down opacity depending.
5. Profit.
Takes a few minutes for the first chip, but each one after is super straight forward.
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