I was curious about all the new colors of poinsettias I’ve been seeing this year so I did a bit of research and found this explanation by Walter Reeves. You can find a link to his website below.  Here is what I read: 

The process of making a colored poinsettia is interesting. Growers start with a plant with light colored (white or pink) bracts. You’re probably aware that the colored parts of a poinsettia are not true leaves – they are modified leaves, called bracts, that serve to attract insects to the tiny yellow flowers at the tip of each branch.

Special dyes are sprayed onto the bracts a few days before the poinsettias are shipped to the retailer. Glitter may be applied as well. A spotted effect is achieved by sprinkling alcohol onto the dyed bracts.

Dyes are available in many colors, so plants can be dyed to match indoor decor or even your college football team colors!

Poinsettia bracts will naturally fall from the plant as it ages this spring. If you keep your plant alive it will produce bracts with the “natural” light color the plant had originally.

On another site, I found this information about what are natural colors for poinsettias: The colored bracts . . .  are most often flaming red but can be orange, pale green, cream, pink, white, or marbled

http://www.walterreeves.com/gardening-q-and-a/poinsettia-dyed-purple/

for Cee’s FOTD