Banded gemstones (6)
I believe the answer is:
agates
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">banded gemstones</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for agates that I've seen before include "Ste aga up for the stones" , "Chalcedonies" , "Stones to be found in a stage" , "Hard coloured stones from a stage" , "Banded semiprecious stones" .)