The materials info page says that full-color sandstone can produce "photorealistic" parts - is that really true?!?! For instance, is the attached photo possible without painting? I'd think that if it was, ShapeWays would show a whole bunch of incredible examples. There's only one example, the "Sad Man" figure, that is fully and realistically colored, but I'm really not clear on whether it was painted or came out of the printer like that. This is the #1 problem with printing scanned objects - they generally look like blobs unless you take a lot of time to paint them.
The colour is printed at 650x540 DPI, so is pretty much the same as what you'd get out of a consumer injet printer. I just took this photo below of my Eyes Die which has 16mm sides - the die was printed in the old Colour Sandstone which used a synthetic 'wax' type sealant (hence the sugar cube type look) - the new FCS uses CA as a sealant and the colours from images on the forums are more vibrant and there looks to be less of a sugar cube look.
You may not be able to tell from the photo, but the surface is slightly grainy and not as smooth as a paper photo, but besides that yes its true, sandstone produces that level of realism out of the printer. It does look like he put a clear coat on the model in the photo above to make it shiny. As long as you can get a good texture in your model, the print will look good. IMO, texturing is the hard part.
The results straight out of the printer can be quite impressive. Check out the various examples under miniatures and discussed in the forums. Here is a 5 cm long model of a house. It has received a coat of a clear varnish, but otherwise is untreated. https://www.shapeways.com/model/621110/1_300_north_german_cot tage.html Greetings Draogoman