0 0 0 0 0 0 0 0 7103.91 Rubies, sapphires and emeralds, worked, whether or not graded, but not strung, mounted or set, rubies, sapphires and emeralds, worked, ungraded, temporarily strung for convenience of transport (excl. rubies, sapphires and emeralds, simply sawn or roughly shaped, imitation precious stones and semi-precious stones) 50