During the weekend when people are dyeing eggs all sorts of lovely colors, I'm thinking of the many colorful coins to be seen.
Tone Morgan dollars have become tremendously popular in the last few years. These coins can come in blazing shades of red, gold, violet, pink, green. Sometimes the impression of the paper wrappers can be seen. I especially recall an 1882-S with violet toning on the obverse, an 1883-O with rainbow toning on the reverse (that I picked out of a box) and an 1885-CC with deep orange color.
Large cent collectors know that their favorites can come in all sots of colors, attractive or not. There are the chocolate brown cents. There are the ones with shades of Mint red. Some have been harshly cleaned and are dull orange.
Matte proof Lincoln cents are seen in lovely tones, due to the sulfur in the paper used to wrap them. I once saw a gorgeous 1910 proof with subtle shades of violet, visible when the coin was turned under a light. I also recall a 1915, possible the best Lincoln cent I've ever seen, shimmering red and violet.
Nickel coins sometimes show a gun-metal blue tone. Buffalo nickels and three-cent nickels come to mind. I once saw a 1945-S War nickel with pink and gold toning on the reverse, and a 1939-S nickel with pale green toning.
Some would say, toned coins show a chemical reaction, and are therefore not desirable. I enjoy the beauty of toned coins. I'm a fan of toned coins.