What does 14k gf stand for?

It stands for gold filled. Gold Filled jewellery is used to describe a specific form of gold plating it is NOT filled with gold but it is an alternative to solid gold jewellery. Gold Filled Jewellery is a solid layer of quality gold heat bonded to an internal jewellers metal. GF jewellery is long lasting and if you take care of your pieces e.g no harsh cleaners and take your jewellery of befor going in bath/shower etc it can last a lifetime