Having been placed in a tumbler, which smoothes out and enhances the luster of a mineral. Rocks and minerals may be naturally tumbled, if they were smoothed and rounded from having been in a fast-flowing stream or river for a long period of time.

Tumbled stones were finished in a tumbler, a mechanical device that smooths and rounds the surfaces of stones. Tumbled stones look very much like stones that have been in a fast-flowing river or stream for a long time.

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