Styling blockquote

Hi, I would like to have closing quotes in my blockquote elements
I’ve tried this code in the CSS:

blockquote:after {
  position: absolute;
  content: "'";
  font-size: 2em;
  bottom: 0;
  right: 0;
  margin-right: 1em;
  margin-bottom: 1em;
  color:white !important;
}

but the closing quote doesn’t look right and if I use character codes the symbol doesn’t appear. Can you help please?
I have purchased a new licence code 🙂