Three species in particular are noted: The Black Beauty, Black Magic and Black Baccara. The first two hold darker red or crimson hues, whilst the Black Baccara is the blackest rose that grows. It is a free flowering, bushy plant that is said to be quite resistant to flower diseases. It ranges from an extremely dark red through dark burgundy to deep red. It is available to purchase from many places online, and most likely in larger garden centres or florists.
The bare root of the flower is available to purchase usually between November and February due to seasonal conditions required to grow the flowers. Garden Roses (www.garden-roses.co.uk/products.asp?partno=1141) deliver Black Baccara roses, and also allow customers to specify certain details prior to ordering, strength of fragrance, height etc.
Whilst growing and tending your own Black Baccara rose bush will be quite hard as the bare root is not available to order until the autumn, it is possible to black your own roses if you have a readily available supply from your own garden or a florist. You'll need to first de-thorn the rose, and then cut the stem so it is open. Place the rose in a vase of water that has been coloured black with some food dye, and leave it for a few days. As the rose absorbs the blackened water from the vase, the colour will reach the petals and turn them a darker hue. This works best with already dark red roses, as it is better to have a very dark scarlet than to turn white roses grey!