You said you did not know much about it.

This chip is on the Richard Edward Staeffler Memorial CA site as: Jacks Place, Marysville, CA.

We could not find a Jack's Place in Marysville, CA. over 250 miles away from Arcata.

Info we found follows:
The address on the Mason order card was for Marino’s Club in Arcata which has a long history, but nothing about gambling. The stories do however show some borderline racy things, so it wouldn’t be out of the question. See link below.

http://www.arcataeye.com/2011/09/remembering-long-lost-marinos-club-%E2%80%93-september-26-2011/

The club was owned by Marino and Emelia Orlandi. It looks like Emelia’s maiden name was Champi, so there would be the link to the order.

I couldn’t find a CJ Champi, but I did see a Silvio J Champi who was later a card dealer in Arcata in the 1970s (at another Ninth Street club). “Toby and Jack’s”, owned by Jack P. Wilson, 764 9th Street, Arcata.

Were the J in Diamond chips used at Marino's Club for non gambling use or maybe some type of gambling? We don't know.
Were they used at Toby and Jack’s in Arcata? We don't know.
Special thanks to Ed Hertel.