Ummm...there isn't a truly 'black' rose, so what you've bought, I can't imagine! Good luck with them, anyway. They'll be years before they flower...

no they will still keep their coulour,just as long you put them in the right place in the garden and let them have enogh sunlight.good luck with the seeds. you may see lots of delightful ladybirds on the flower making sure that the rose shredders(aphids:greenfly) are kept under controll

Never heard of anybody growing roses from seed before - it will be interesting to hear how you go on with them.

Would have thought it highly unlikely that roses would come true from seed...

I'm afraid I agree with Moongrower, but time will tell, if you have a LOT of patience.