The recommended term for a diamond without external or internal flaws or blemishes when viewed by a trained eye under efficient illumination and under a fully corrected magnifier of not less than 10x power; binocular examination under dark-field illumination is preferred. The American Gem Society advocates the use of the term "Flawless" by its members, while at the same time denying them the use of the term flawless, but only if a stone conforms to its definition of the word perfect, without reference to make or colour.