Loose Clear Seaham Sea Glass/Loose Durham Sea Glass/Loose Sea Glass/Seaham Sea Glass/Sea Glass Gem Stones Ref 139 Clear Durham Sea Glass. Round Brilliant Cut. 16.2 mm diameter, Weight 12.8 carat. Clear and sparkling. Cut from a sea washed glass pebble found on the beach at Seaham on the North East coast of England. This stone is of exceptional size and clarity, a truly one-off gem.