Nightstone Unlimited is the corporation founded by Demona and Thailog while they were in Paris, combining their accumulated wealth and using their "human aliases" of Dominique Destine and Alexander Thailog.
Nightstone will still exist in some form in 2198.
The corporation focuses strongly on genetic research, and in particular, created the CV-1000 Carrier Virus in order for Demona to carry out her failed Operation Clean Slate plan. ("Hunter's Moon") The Clones were also created at the Nightstone Unlimited building in Manhattan. ("The Reckoning") Demona/Dominique Destine has seemingly abandoned it following the events of the Hunter's Moon, and Alexander Thailog now operates it solo (by speaker-phone, memo and e-mail to keep his nature a secret) . Sevarius has often been hired by Nightstone to work on various projects.
Demona came up with the name Nightstone Unlimited and Thailog liked the sound of it.