Understanding the 'cTo' Mark on a Gold Service Award Ring

Question
After his passing last December, I was given my father-in-law's service award ring from KOCH Oil Company. Inside the band, it has  cTo  10K. I understand that the 10K is the gold quality, but I'd like to know about the cTo mark. If you could help me, I would greatly

Answer
Hello Harold and thank you for your inquiry. I have not been able to find a cTo company or manufacturer mark in my resources but will keep your inquiry active and let you know if I find something. They were probably a company that specialized in service rings and jewelry. If you know where he worked for the company, you may be able to contact them for any archive information. You should have your ring authenticated - checked for gold and gram weight especially since it is an heirloom . Keep any documentation or information on the ring for future recipients and enjoy it now !

Sally
jarrettsjade.com