The letter A refers to the date, this is called the date mark. The date depends on the shape of the letter, do you have a picture?
The Star Hallmark has often been connected to Russia, however it could also mean 'Star of America' or 'Star of Alaska' or even 'Star of Artemis'. Any of these could explain the star. It could also be reference to someone's name, such as 'star? ?All my love'.
