GST rate on synthetic stones reduced, applying concessional treatment to unworked, unmounted and temporarily strung items. Classification 7104 applies a concessional GST @ 0.25% to synthetic or reconstructed precious and semi precious stones (other than diamonds) whether or not worked or graded but not strung, mounted or set; to ungraded synthetic or reconstructed stones temporarily strung for transport; and to synthetic or reconstructed diamonds that are unworked or roughly shaped.