Porphyry is best known as an Italian stone however similar material can be sourced from South America and China (Chinese porphyry).
Chinese porphyry does not naturally occur as a mixed colour pallet so must be specified as a percentage of various colours. The advantage of this is that you can choose the pallet you require. Another major difference between Italian and Chinese porphyry is that the Italian material is riven top and bottom and therefore varies in thickness, further more it is difficult to get Italian porphyry over 100mm thick in any significant quantities.
Chinese Porphyry is manufactured in the same way as granite, raw block being cut to size and then a flamed or bush hammered on the finished face. This gives the advantage of being able to supply deep setts with sawn sides which would not be possible with Italian material.