Earliest Use of Diamond

It has been long thought that man first used diamond in India, around the time of Christ, based on the record of documents from India in the latter half of the first millennium, BC; there appears to be no evidence of diamond usage from either earlier historical periods, or prehistoric times. However, we have uncovered evidence that the neolithic Chinese were using diamonds to polish a special group of ceremonial stone burial axes as early as 2500 BC, placing the earliest known use of diamond two thousand years before the mineral is known to have been used elsewhere. This particular group of stone axes are made predominantly of the mineral corundum, more commonly known in its gem forms of ruby and sapphire. Unpolished, rougher versions of similar axes made from the same stone appear as early as 4000 BC, pushing back the first known use of the mineral corundum to that time, millennia earlier than what had been thought previously. Both of these minerals are substantially harder than the mineral nephrite, the principal component of ancient Chinese jades. Our work may therefore shed light on how large numbers of highly-polished jade burial artifacts were made, an enduring mystery of the material culture of the Chinese neolithic.