I wanted to know if the ring will nullify even the good effects of lord Shani from their lives.
If Shani dev really done good to you, and if you are sure, then can wear an iron ring. But, iron element would not be good for health, as it reduces magnetic energies inside the body.
Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.