diamond in the rough

diamond in the rough idiom
Also, a rough diamond. A person of exceptional character or potential but lacking polish and refinement. For example, Jack is intelligent and trustworthy but lacks manners—he's a diamond in the rough. [Early 1600s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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