170. Where the bailee has, in accordance with the purpose of the bailment, rendered any service involving the exercise of labour or skill in respect of the goods bailed, he has, in the absence of a contract to the contrary, a right to retain such goods until he receives due remuneration for the services he has rendered in respect of them.Illustrations (a) A delivers a rough diamond to B, A jeweller, to be cut and polished, which is accordingly done. B is entitled to retain the stone till he is paid for the services he has rendered. (b) A gives cloth to B, a tailor, to make into a coat. B promises A to deliver the coat as soon as it is finished, and to give a three months' credit for the price. B is not entitled to retain the coat until he is paid.