Known as one of the five "shield rings" the ring in question was an invisbility ring, or a light diversion ring, which granted the wearer ... duh!!! INVISIBILITY! by use of projecting a light diversion field.. -grins-
"Of course," I said, "it is the ring which I obtained in the Tahari, that ring which projects the light diversion field, which renders its wearer invisible in the normal visible range of the spectrum."
I looked at the ring …" If this is an invisibility ring, we are fortunate to have it fall into our grasp," I said. — Explorers of Gor, pages 27-28.
Shaba, the thief, simply wanted to explore the jungles along the Ua River, et al, and, ultimately, the source of the Ua, so that he would be the first to fully map the region and become famous. He fully expected to be followed, predicting his ultimate death, with the knowledge that his pursuer would find all his maps and return them to civilization to be published and his name placed in the annals of Gorean history and renown.