Antique 1800's Slate Multi-Colored Chess Board.

From a dr's estate. the family is just sitting out stuff for 1-2 dollars . Apperantly he was a Collector of everything. (Rich Horder) This multi colored chess board is in good condition, minor scratches on top. Veryinterested in finding more about this Chess Board. First of all has it been painted then coated? Who was the Maker/MFG.? I seen one on ebay but no information, Just rare. Well being rare should carry some information on it. Any help would be appreciated.