It is totally amazing what a few colors can create. A friend of mine is a house painter and over the years I have given him a hand when he needs an extra pair and I can spare the time. I look at his paint chart samples that are literally hundreds of variations of hues and in the paint store they mix all that from a dozen or so base colors. It never ceases to amaze me. As far as the old masters are concerned they also were famous for thin washes (translucent layers) that held some pigment yet let the layer below it show through.
Apparently one of the colors favored by many of the Old Masters was what is today marketed by art suppliers in tubes as "cold black." Interestingly, it is almost the same color as "lampblack," which is one of the tints used by by paint stores in mixing up their colors. It is a black that, when a little white is mixed in, makes a gray with a distinctly blueish cast. When used alongside the earth tones that dominated in those days, it is amazingly blue, and even makes a green when added to yellow.