There are a few places in the world where you can get really good quality, well tumbled seaglass and one of the places in the UK is Seaham Beach near Durham. In the early 1900's there was a glass factory in Seaham and the slag glass used to be disposed of in the sea. Over the past 100 years and more this glass has been tumbled by the North Sea and can be found on the beach as the tide goes out. Lots of clear glass mostly but sometimes some coloured glass as well. This piece of glass was found by me on a trip back in Sept 2023 and was just crying out to be made into this gorgeous but simple pendant. 
 
I have set the glass into sterling silver wire and hung it from an 18" sterling silver chain. This is a gorgeous addition to anyone's jewellery collection and a true one of a kind necklace.