How much do the black industrial diamonds cost?

Seventy-five percent of diamonds that are mined are used in industry. These diamonds are not gem-quality stones, and appear cloudy, even milky because of their flaws and inclusions.

'Black diamonds', properly Carbonado, are gem-quality stones.

You can read more, below, and depending on whether you want to employ your 'black industrial diamond' as a gem stone or as an industrial tool, you can pay accordingly.