Simple past tense and past participle of gem. (verb)
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Use "gemmed" in a sentence
"“Look at this,” says my mother, holding up an elaborately gemmed and frilly princess gown."
"The roadway had become a flowing ribbon of silk, gemmed with yellow cat-like eyes that floated past wary and curious in their regard for him and his nervous horse."
"His rimed brows turned to cataracts as he whirled about; his mustache, still frozen, seemed gemmed with diamonds and turned the light in varicolored rays; while the flying feet slipped on the chunks of ice which rattled from his moccasins and German socks."