Ancient Roman ring, possibly decorated with a Christian cross, from an old collection of Celtiberian items

This majestic ancient ring has a cross on its center and two slanting lines above the cross; it may be Christian, although some of the other items in the collection pre-date Christ. The ring appears to be darkened bronze (possibly, some of the scratches seem to have a silver color... I'm not sure if it's brass or a silverish metal) and the ring an oval shape, measuring on the inside 19.27 (approx. size 9 1/4). This ring is not perfectly round, and without adjustment would be less desirable to wear (I can slip it on, and it will stay on my dad hands, but it is noticeably not round).

The ring is probably an ancient Celtic or Roman ring, from the Iberian Peninsula, and likely bronze (as the other artifacts in the collection are).

We bought a collection of ancient artifacts at auction in Switzerland (La Galerie Numismatique, September 28th, 2024); we are researching each object and offering them for sale individually. You can see the collection in the pictures we posted.

Measurement -
The ring measures approx. 19.27mm across the inside.
The ring measures approx. 22.38mm across the outside.
The ring measures approx. 11.67mm tall.

Provenance -
In the course of our investigation, we found that the artifacts had several names of places in the Celtiberian region written on them, for example "Salienca" is written on the base of one of the rings. Also, the brooch design was unique to the Celtiberians (Google search Celtiberian Brooch to see similar examples). We've come to the conclusion that the collection is specific to the Celtiberian era/region although some noticeably Roman brooches are included within the collection, so it spans many centuries.

Wikipedia states the Celtiberians "were a group of Celts and Celticized peoples inhabiting an area in the central-northeastern Iberian Peninsula during the final centuries of the BC. They were explicitly mentioned as being Celts by several classic authors (e.g. Strabo)."

Condition -
See pictures. This ring does not seem to be polished and has dirt inside the cross and on the back side of the face. The ring has a few scratches on the inside. The ring is darkened with oxidation. There is black marker on one side, presumably saying where it was found (difficult to read... possibly "Corraletes"). Many of the items in the collection were similarly labelled.