Years ago, class could easily be attributed to any film star; women like Audrey Hepburn and Grace Kelly had an almost innate sense of grace and class, they were so refined in their work and style.
These days, it seems many actresses are more trashy than classy. I used to admire classy women, but sometimes is can be so anal and boring.
Many people would define Nicole Kidman as classy for instance, but she seems so frigid and uptight to me.
But all in all, class is not tangible, in my opinion - it's about grace and style, which can only come from within.