According to a bill now signed into law, students who took the Georgia high school graduation tests after 1994 but did not pass, and subsequently did not receive a high school diploma because of not passing the tests, are eligible now to get a retroactive high school diploma. According to the law, the diplomas are to be issued by the local school districts and dated retroactively. A person in this position will need to petition the local school board to determine eligibility for the retroactive diploma.
Here's an article with more information: http://getschooled.blog.ajc.com/2015/03/30/governor-signs-bill-today-enabling-8000-georgians-to-receive-high-school-diploma/?ecmp=ajc_social_facebook_2014_sfp
Here's the text of the law (formerly House Bill 91). See Section 5 starting on page 7: http://www.legis.ga.gov/Legislation/20152016/152497.pdf