Permalink Reply by Rich on January 17, 2013 at 12:47pm
Looks like they work with a number of different baseball players - you might be able to cross-refernce this by seeing if the athlete has any confirmation of this on their website or if there is any other documentation of signings with Onyx.
Unfortunately, I've never heard of them, but I've kinda been out of the card collecting hobby for a while and am not a huge baseball enthusiast. Honestly, my first impression is that it doesn't look shady though.
Maybe you could ask about the particular signature you're looking into. There are a lot of sports collectors on this forum, and some of them might be able to validate the signature itself.