The word diamagnetism is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 22
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (71 words)
against, agatine, agatise, agendas, amentia, ammines, amnesia, animate, animism, animist, damages, damming, dammits, destain, detains, diamine, dieting, dimmest, dimming, dingies, editing, enigmas, gamiest, gateman, ignited, ignites, imagine, indites, inmates, instead, magenta, magnate, magnets, maidens, maiming, managed, manages, mandate, manmade, matings, medians, midgets, mindset, miniate, minimas, mintage, misdate, misedit, mismade, mismate, misname, mistime, misting, nametag, sainted, seamaid, seaming, seating, sideman, sigmate, smidgen, smidgin, smiting, stained, stamina, stimied, tandems, teaming, teasing, tidings, timings