"Not boring old grey!" That's exactly what the people of Florence would have thought of Brunelleschi using cheap local grey stone for the ornamental mouldings of the Ospedale degli Innocenti (foundling hospital) he started designing in 1419. The only stone worthy of ornamentation was Tuscany's brilliant white and green marble. Grey stone was what builders used to make sewers!
But then, it was a lowly kind of ornamentation that Brunelleschi envisioned. Instead of triglyphs and maters, he was having his masons copy the entablatures and columns he saw on ruins left by the Romans, ruins that were over a thousand years old by that time. Not only were they daggy and crumbling, to Christian eyes they were pagan... abhorrent! It would be like us copying ruins left by the Nazis!
Looking back now though, we can say it was the start of a period of rational reflection, replacing the medieval Christian period when architecture instilled wonder and terror. Whether it's on Brunelleschi's facade, or used by Michelangelo to make the stairs of the Laurentian Library (one of my own travel sketches below) Florentine grey stone invites calm observation of sculptural forms, by revealing those forms to our eyes.
Grey doesn't make the eye squint like polished white marble, or confuse the mind the way patterns or darker colours can do. It is not white you should be afraid of, if you're not one to have your figure revealed. The colour to choose if you are an extroverted woman, is "sea mist", or light grey.