Complex sentence: Colonies are white and velvety at first, generally less than 1 mm high, but soon turn grey or green-ish grey, starting from the center, then purplish brown and black, often with pink or vinaceous diffusing pigment.
Split into simpler sentences: Colonies are white and velvety at first, generally less than 1 mm high. They soon turn grey or green-ish grey, starting from the center, then purplish brown and black, often with pink or vinaceous diffusing pigment.