LONDON (Reuters) – In a London studio, British artist Carne Griffiths adds the final fluorescent pink touches to “The Platinum Queen”, a portrait depicting the young Queen Elizabeth shortly before her coronation almost seven decades ago. Griffiths, known for using tea, ink and alcohol in his work, is releasing 70 limited edition prints – as well as artist proofs – to mark the monarch’s Platinum Jubilee, one for each year of her historic reign. Based on an original painting sold last year, each piece is made with layers that include diamond dust and platinum leaf. “I thought this was a poignant…