Welcome! 
Dark Red pirate glass also known as Black glass. This piece is very rare and I will probably never find another- especially this large. I picked it up assuming it was a lovely brown. It became obvious it was actually bright red when I lifted it to the sun. ❤️ 
I did this because when you find Seaglass this dark - aka Black Glass- you don't know the actual color until you shine a light through it. Unfortunately it also makes it difficult to photograph. 🤔 
I did my best here. It is a wonderful deep cranberry red in the light. And if you were wondering...yes...I screamed when I saw it's true color. 😊
My Seaglass pieces are made from genuine, ocean tumbled Seaglass that has been searched out and collected over many years by myself from New England beaches in the U. S.  
These pieces were found in the condition you see here. The only thing different is the tiny hole drilled for the hand made, sterling silver, custom bail that I create for each piece. 
Your pendant will come on a hand waxed cotton cord, finished with a lobster claw clasp. 
There really is nothing quite like a real piece of seaglass. ❤️ 
'Genuine Seaglass'
~Be wary of people selling machine tumbled glass as genuine. Some obvious signs are very finished pieces selling cheaply and many exotic colors. Bright and deep colors are very rare in genuine seaglass and real collectors typically don't part with these colors cheaply as it likely took many years to find and they may never find it again. 
As always if you have any questions feel free to email me at: KeepingPieces@gmail.com
Thanks so much for stopping by my little collection. 
Christine