About 10 years ago,  brides were using a lot of color in their headpiece.  Often they would pick up the colors in their wedding color scheme.  Sometimes they would pick up the color in the trimmings of their gown.  Some brides would even try to accentuate their eye color via their headpiece color.  

This trend abruptly changed to almost exclusively all white , ivory or pure crystal headpieces.  Personally, I think an extremely subtle amount of color can be gorgeous.  The color has to come from very high quality sources.  Either the tiniest perfect peridot, acquamarine, rose quartz, or other gemstone, the tiniest of Swarovski crystals can add a very pretty depth of interest to a headpiece.   

In general, color is still rarely chosen by brides.  Because trends are cyclical, I believe we are on the cusp of a return to color.  However, for the bride completely disinterested in the trends, a splash of the most subtle color might be just perfect for  her headpiece.

As always, you as the bride, dictate your taste preferences.  Always choose what you want and love as your look on your wedding day.