why are polished gems so much smaller than the raw, unpolished stones that they came from?

Question

I went get mining for the first time last year and after we were finished, they gave us the option of getting a stone of our choice polished for free. The finished product was maybe 5% of the size of the original stone that they polished. Why is so much of the material lost during the polishing process?

In: 3

Answer 1

Most of a raw gem is simply not suitable for use as a decorative gem stone. So you have to cut all that stuff away, then cut it into the desired shape, then polish it.