It is the manufacturers logo.
It is required on all NV chips by NV gaming. If a casino does not use that mold then manufactures initials are required on the chip either in UV or print.

H&C mold designed by Bud Jones for Christy Jones in ST Louis back in the 1950's.
Christy Jones splitup in 1964.
Bill Christy got the H&C mold in the split.

Bill Christy opened sales in Las Vegas in 1964.
He later sold out to Paul Endy. Endy started business as Paul-Son Gaming.

He became the largest seller of gaming chips using the H&C mold.

In 2001 Paul-Son sold out to Bourgogne Et Grasset in France.
They became Gaming Partners International or GPI. Still sell out of Bill Christys same location in Las Vegas.

In the early years H&C chips were actually made at The Burt Co in Maine.

Paul Endy moved production to Las Vegas and later to Mexico where they are made today.

Probably more than you wanted to know.