In Louisiana it appears that embossing, ink, and computer-generated stamps are all acceptable. No mention of any color requirements. The rules are mainly written for use of embossers, but go on to state that rubber and computer-generated seals of the same design and size are acceptable.
IMO, an ink stamp seems much more practical, but an embossing stamp is just SO MUCH cooler.
To be honest, I don't have any immediate plans to actually stamp anything. If I wasn't required to get a stamp, I probably wouldn't.