It seems to be a synthetic lacquer. Don't believe it's poly although it can be treated the same for some things. If your pointing up the checkering the finish type is not relevant. Touch up the checkering after it's cleaned up with whatever suits you. I usually prefer tung oil or TruOil for this. They don't clog the checkering as badly as most poly finishes. The new rubbing poly finish is the exception. It may well work the best of all.
