This is a heavy sterling silver pebble. My silver raw materials are all recycled in the UK by the supplier anyway, but these are made from recycled offcuts. 
The scrap is weighed and melted into an organic shaped pebble. It's flattened with a rolling mills and the face is sanded. It's stamped, jump ring is added, then polished. 
It's set on an 18 inch sterling silver belcher chain. 
Sent giftboxed, tracked 1st class postage included. 
Approx 1.8 cm