Banded gemstone (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">banded gemstone</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for onyx that I've seen before include "Form of chalcedony" , "Stone-like marble with different colours in layers" , "Black variety of quartz" , "Quartz with alternating bands of colour" , "Chalcedony agate" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">banded gemstone</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for agate that I've seen before include "Semi-precious quartz" , "Decorative stone" , "Precious stone" , "Semi-transparent stone" , "Onyx" .)