January birthstone (6)
I believe the answer is:
garnet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">january birthstone</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 garnet that I've seen before include "Precious stone, usually red" , "Deep red precious stone" , "Glassy red, yellow or green gemstone" , "Semi-precious stone of deep transparent red" , "Semi-precious stone of argent type" .)