A fascinating piece of archaeology at http://siberiantimes.com/science/casestudy/features/f0100-stone-bracelet… …
a stone bracelet from 40,000 years ago – made of a polished green stone. It was unearthed in 2009 but only now have Russian archaeologists accepted its great age. It was found in the Denisova Cave in the Altai, renowned for its Palaeolithic discoveries. The bracelet was found in the same layer as the prehistoric remains.
It is the techniques involved in making the bracelet that have made archaeologists sit up. It involved drilling through the stone with an implement, and a boring tool (like a rasp), and the ability to polish the stone – using a buffer of some kind (probably skins subject to varying degrees of tanning).