[posterboy]

If you look at marble statues, a square box is hardly amazing in comparison. "a few ten-thousandths of an inch" - close to micro meter precision - sounds almost like exaggeration, but some type of stone might just split in a very planar way.

[williamblake]

Yes, there are some amazing marble statues. Have you seen the one where there is a fishing net cut from marble? Or the twins from Russia - two identical statues except for some obvious clumps of hair of hair, as if an image was taken at different times, in the breeze, and an artist or machine reproduced the statue from the image. I am assuming that most marble statues are at least an order of magnitude less precise than the granite box. Granite, by the way, is composed of different materials, such as, for example, feldspar and quartz. It doesn't break along a plane. Yes, a micrometer is .0001". Calipers, on the other hand, often only measure to .001" and would not be able to measure anything this precise.

[sedachv]

> "a few ten-thousandths of an inch" - close to micro meter precision - sounds almost like exaggeration, but some type of stone might just split in a very planar way.

Not an exaggeration, just an extremely long time spent hand grinding/polishing with fine grit tools/paste.