Ring with coral cabochon

Ring with coral cabochon ca. 25x13 mm, 1 small brilliant-cut diamond ca. 0.04 ct, 18K YG, 15.7 gr, ring size 56, 2nd half 20th century, minor signs of wear, coral slightly loose but secure in the setting, maker's mark 'thoma'. IMPORT/EXPORT RESTRICTIONS OUTSIDE THE EU!