Agatha Christie and a Mystery

Today is Agatha Christie's birthday, she was born September 15, 1895.  She is one of my favorite authors and I think, but only think, because I'm always finding more, that I've read all of her books and short stories.  The Guinness Book of records says she's the best selling author of all time having sold more than 2 billion books.  Her estate says she's third, behind Shakespeare and the Bible.  Her most popular books is And Then There Were None, which I just recently read, but my favorite is Witness for the Prosecution. Her play The Mousetrap  is the longest running play of the modern era.  It opened in 1952 and has been running ever since.  We saw it way back in the 70's or 80's in London.
Though she has shot people, stabbed people, hung people and electrocuted people,  she was the very best at poisoning them.  She served as a volunteer nurse in the first world war and was trained as an apprentice apothecary or dispenser.  The knowledge she gained there served her well.
She was married twice.  Her first husband had an affair and wanted a divorce, Agatha was heartbroken and disappeared for 11 days.  It became a cause célébre and the world was shocked, all the newspapers covered her disappearance, the police suspected her husband of doing away with her---sounds a bit like Gone Girl doesn't it.  Agatha never said where she had disappeared to, but a number of books have written about it.  I read  Agatha Christie and the Missing Eleven Days, it gives a pretty detailed account of what happened.

Unfortunately her second marriage to archeologist Max Mallowen was also unhappy (he had a long running affair with his secretary).though she stayed married to him the rest of her life.

I think her writing must have been her way of leading a happier life, I know that her books have brought a lot of reading pleasure to me.

Now the mystery.  When we were in London recently Mac went mudlarking along the foreshore of the Thames and picked up bits and pieces of things to add to his collection and one of his finds has him stumped and Lord knows I'm no help.  It's a round piece of green glass about 1 1/2 across and a 1/4 inch thick.  It has an eagle sitting on a crown and there's  a crown above the writing.  He thinks the writing is Latin.  Take a look and let us know what you think, we just don't know.