While no true black rose exists in nature (or any other black flower for that matter), many florists produce the unique black rose through a dying process. However, there are also some deep red shades of roses that have such a deep color that they are interpreted as black.
Should you give black roses? Black roses may seem mysterious and elegant, but definitely be cautious when giving them as a romantic gesture. Black roses are sometimes sent as a gesture to end a relationship. While the meaning of the black rose is actually renewal, it's not often seen that way when it comes to a relationship, particularly new relationships. Most people tend to associate the color with "death" or in a romantic situation "death of a relationship". If you do send black roses, make sure that the recipient won't interpret it this way, unless that is your intention. Sometimes giving just a single black rose can symbolize a mysterious and powerful romance.
In fact, unless your sweetie has a sense of humor, loves the color black, or the color has some sort of special meaning to you both, we recommend not sending a black rose at all. One other exception may be sending them as a Halloween gift - perhaps a single black rose when you pick her up for a costume party - as black's the traditional 'spooky' color of the holiday.