koryo celadon vase

we have been in the business of genuine antiques and specialising in chinese antique porcelain for quite sometime and this is the only item we handle not of chinese origin.According to our source who acts as our tipster on excavation site they accidentally found this in a cave with other war items of japanese soldiers in world war II which is near the digging sites of chinese antiques.We made some research and we found out that this is a antique koryo celadon from korea with bird design as the subject.We want to know the value of the item.