Porcelain tiles have been used on exterior "rain screen" or 'ventilated"  facades of multi story buildings in Russia and Eastern Europe using exposed mechanical fasteners.  The exposed fasteners and the end result are, shall we say, molto brutto, and I would not recommend this.

The tiles can be custom manufactured with thickened attachment points, but this is not practical for small lots and adds to the cost.  The tiles themselves are fine for exterior use, but attachment is problematic.

The other problem with these tiles (or any thin stone) is how does an outside corner look with material 1cm or less?  Unless you have "L" shaped corner pieces, everone knows that it is thin.  I have never looked at exterior "faux limestone" products such as you mention, but it looks like the manufactured stones probably have such pieces.

I am lucky that my build will be north of San Antonio where limestone is (relatively) inexpensive:-)

Bruce

Jelly, I am a manufacturer of thin stone in South Carolina and I can give you the basics of its green-ness.  Our process takes natural stone and at a minimum doubles its coverage area.  It will typically quadruple its coverage area.  We also recycle all of our water used in the production process.  The scrap that is left over can be used in backfill applications or as a gravel type of application.  There are no chemicals or dyes used in the process.  The product is applied in a similar manner as the fake stone and is comparable in price.  Obviously I am biased but when comparing the benefits of natural thin stone, fake stone, and full dimension natural stone, thin stone takes the best of both and combines into one product.  I hope this provides some helpful information. 

Jelly, what is the name of your company in SC?

I agree with everything 3river noted about the green benefits of natural thin veneer.  Most, if not all, manufactured or cultured stone products are basically colored cement. It has been well documented that cement production is very energy intensive—cement is among the most energy-intensive materials used in the construction industry and a major contributor to CO 2 in the atmosphere.

In terms of cost, please consider the cost of the entire project, not just the cost per square foot.  Some other cost benefits to consider are maintenance. Natural stone is maintenance free, unlike manufactured or cultured stone, natural thin stone veneer will not fade or wick water, thereby avoiding homeowners costly repairs in the future.