It is a FLAT TOP 5 simular to codes IN-D_ or IN-E_ or IN-F_ on page 160 & 161 Seymour Revised Edition.
It sure looks like an Ivory chip and without seeing it I would say it is in fact Ivory.
IMHO: The ring is suspect but it could be a legit 5 BUT... I think the ROCK ISLAND LINE is probably recently Laser Cut. If you compare the ROCK to the other words it appears that it is slightly lighter and by the time they got to the LINE the intensity if the laser looks like it might have been adjusted.

It might have been a nice uncoded 5 but IMHO it is a nice "recreation." Either way it is a fake. It was probably a Blank or a Red Blank or at best an 5 before it was altered. Just my opinion.