How to increase the shade of some dark stones?
Some dark stones (Marquinto Black, Zimbabwe Black, etc.) often have dull shades, which need to be livened up to make them acceptable and marketable. So, they are treated with hydrocarbon solutions made of polymers that penetrate the crystalline habit, giving them a permanent wet look, which darkens the material. The best results can be obtained by using mixtures of silicone and acrylic polymers.
