It's BS421 in the Carpenter and Grayson Peanut Butter Collectors book. The paint is in pristine condition with no bubbling or missing paint.
Here is a Boscul 5" Blue with yellow centers Michaelmas Daisy Peanut Butter Tumbler. It's in excellent condition with no chips, cracks, scratches, or stains on the glass. The paint is in pristine condition with no bubbling or missing paint.
If you are a collector using the 3rd edition collectors book by Barbara Mauzy, you can find this particular glass on page 71.