The term 'surface of a cut gemstone' can be summarized by the word 'FACET, ' which is a five-letter word. A FACET is a flat surface on a cut gemstone, usually with a specific angle and shape. Faceting is the process of cutting and polishing the surfaces of a gemstone to create a symmetrical and attractive appearance. Faceting is an important part of the gemstone cutting process, as it can enhance the beauty of the stone and increase its value.