I found a dark blue stone on the beach and thought it was beach glass but I don't think so. Its soft, maybe a 3 on the Mohs scale. Top photo is take dry and bottom is take when the stone is wet.
I'm starting to think it is sea glass. Its has little bubbles inside and is fairly translucent. When held up to a light bulb you can see a bit of marbling of the blue inside. No fractures are present. I will try for a photo with the back light.