Tough call! As you probably already know, rings come in all shapes, sizes and have various metallic alloys. The electrical conductivity of Tungsten is 28% that of silver, with an equal mass. What that means is, if you had a silver ring that provided a 36 as a TID number, a similar sized (and shaped) ring made of Tungsten would provide a TID around 8 or 10 on the X-70 or 705. So again, depending on the size, shape and whatever alloy they used to harden the Tungsten ring, I'd expect it to provide a TID of something less than a nickel (12). If I were looking for it, I'd set my X-705 up to reject all the negative numbers and all positive numbers above a 20. At least for the first couple passes over the area. If I didn't find it then, I'd accept all the positive numbers except +48 and cover the ground from every conceivable direction. In either regard, if it was just recently lost, I'd pick up all the surface targets that gave an audio response. You may end up digging a lot of shallow aluminum trash, foil and assorted coins. If you have an electronic probe, it could be a big help on pinpointing surface targets. Unfortunately, without knowing the particulars of this ring's size, shape and precise alloy combination, it is virtually impossible to know exactly what it will come in at on the TID. Sorry I couldn't be of more help. But let us know how it works out. HH Randy