This lightning bolt is made with "Vitrite sea glass".  I've only ever seen it on one beach, and I had asked another beach-goer if they knew what it was. She said that general electric had at one point used the material as an insulator in their light bulbs. It's so so hard to find, and I only noticed it because it was more "glittery" than the other black stones. But when you look at it in bright sunlight, you can JUST see the faint purple glow of the glass.
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This bolt is wrapped in a simple bezel with 3 added silver drops to one side.
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 Approximately 1" long. 
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While cutting, a fair sized air bubble was exposed. I filled it with silver dust to compliment the glittery appearance of the glass and prevent further cracking.