how to create artificial stone

Lotsa manufacturing approaches are available -- I would start by 1: Art supply houses for moulding kits - usually rtv silicone etc. and 2: a marine supply that sells something like the "WEST SYSTEM" which includes epoxy resin, hardener, accelerator, filler etc. so that you can custom compound your casting material -- it is "rocket science" but in this case, the foundation work is already done for you ---- using a liquid epoxy and catalyst with the filler of your choice (industrial waste if you wish) you can come up with "genuine reconstituted jade, or the precious/semi-precious materiel" castings of your choice. This is all within the reach of a kitchen/small shop setup -- been there done that - had lotsa fun!!

as Gnome suggested, there are numerous approaches.

The epoxies will vary from 100% plastic to 100% powdered stone

experimentattion will determine the ratio you need to get the final finish. stone is cheap, but 100% stone breaks aparts too easily

Most artificial marble countertops, baths, etc are either epoxy or polyester resin. streaking the liquid before it sets with reds, blues, etc gives the cured resin the "marble" look. One can also add stone dust, carcium carbonate, barium sulfate etc to further create the "artificial stone" look.

the resin and catalyst used with glass fiber to make 'fiberglas' can be mixed and used pretty (without the glass) easily up to about 60-70 % calcium carbonate or talc which is fairly inexpensive for trials - a single color but could be easily tinted or stained. 'Molds' can be made from silicone and urethane from carved or molded models - some potential sources -

first for learning - a little on polyester, vinyl ester and epoxies -

http://www.fibreglast.com/contentpages-main-Learning-Center-283.html

and for some mold making materials -

http://www.smooth-on.com/liqrubr.htm and the like -

good luck -