When should you use a full color business card?  Here are some suggestions.

Using a full color business card (sometimes called by printers as "4 color process") can be  worth the additional printing cost if your service business solution can be demonstrated in a "colorful" way. 

Your service, by nature, is colorful.  If you are are a florist, an artisan, or an interior designer (as examples), then perhaps a photo or other graphics an be best displayed in a full color business card.

You can demonstrate results better by color.   Perhaps you are an auto detailer or provide cleaning services and can provide a "before and after" type photo or illustration.

Just grab attention.  If you have a good graphic designer for your business card, he or she can perhaps capture some attention by using lots of color on your card.   If so, and you want to invest in the cost...do it!  But just make sure that the color doesn't interfere with making it easy for a prospective buyer to contact you. 

full color business cards