Would it be safe to go into Tess and contact the other trademark holders NOT related to Diamond Jewelry to solicit the sale of my domain? or am I asking for trouble?
I have two situations similar to this type of fact pattern. On the one hand, seeking expressions of interest from others who might be interested in the domain name, while the domain name is being used for a non-infringing purpose,
should be fine.
From the perspective of the folks you'd be contacting, though, the situation appears to be very different, and in observing these sorts of situations over the years, they will nearly uniformly attempt to work your contact into a cybersquatting claim. When that happens, the best you can hope for is that they pursue a UDRP, since a court action will grind you down regardless of the merit of your position.
One of the leading cases where this sort of thing has gone south is
Virtual Works, Inc. v. Volkswagen of America, Inc., 238 F.3d 264 (4th Cir. 2001). Virtual Works Inc. was a software development company which had for years used vw.net. When they were winding up the company, they were contacted by a local Volkswagen dealership to see if they would be interested in selling the domain name. Thinking that the VW corporate parent would likely prefer to have the domain name instead of a local dealer, the Virtual Works folks contacted Volkwagen to see if they wanted to buy it...
http://court.osdir.com/F3/238/238.F3d.264.html
Berryhill did a great job of defending it
Thanks, but.... a chimpanzee could have defended that case.
Although chimps can be a bit unpredictable. Orangutans are generally more focused, but if you want to be more aggressive, try a baboon.