22 k signet ring with compartment on the inside

I have an old gold ring that has always intrigued me. It has the following marks -there is a stamped 22K Followed by an indented rectangle with the initials JPL, next there is an indented oval with raised AR followed by 22K. Each 22K mark has the K in the wrong direction (bent leg on the left straight leg on the right. I imagine the little compartment at one time held a few hairs of a loved one.