1. A method comprising: applying a first optical test with a first optical recipe to a manufactured product to identify a first set of product defect candidates; applying a second optical test with a second optical recipe to the manufactured product to identify a second set of product defect candidates, the second optical recipe being different from the first optical recipe; and generating a first filtered defect candidate set by eliminating defect candidates from the first set of product defect candidates that are not in the second set of product defect candidates, the first filtered defect candidate set comprising at least one defect candidate; wherein the first optical recipe has a higher sensitivity to transmitted light than to reflected light and the second optical recipe has a higher sensitivity to reflected light than to transmitted light.