These rings are only a question due to their new popularity. We must realize this false correlation: that which is popular, is credible. Popularity in no way validates. If this were so, fabricated religions with mass popularity like Christianity and Islam should be more credible than Judaism. However, an intelligent person examines the phenomenon, and decides its worth based on the matter alone.
Why they cannot work: Natural Argument
Amulets cannot work. For if one ignores his flaws – the true culprits of his/her problems – the resulting inevitable problems remain. Thus, wearing such rings while continuing to slack off at work, will not help retain employment; the slacker will continually be fired from job to job. One who eats harmfully will remain sick, despite wearing these rings. Conversely, if the slacker shapes up, and the person eats healthfully, despite not wearing these rings, both will find greater success.
Why they cannot work: Divine Argument
Our merit and sins are what causes our reward or punishment. By wearing these rings, one heretically confesses that God does not run the world justly, and that any evil person can be divinely-shielded from harm by wearing a ring, and that righteous people who don't wear the ring, will be divinely subjected to harm, without having sinned.
This presents an unjust view of the Creator and denies the fundamental of "Reward & Punishment" that permeates all of Torah.
Denies God's Torah
God commanded against these falsehoods, referred to as Nichush (Lev. 19:26); the gauging of our actions based on unrelated phenomena. God granted mankind five senses, precisely so we use them to determine what causes 'X', and what does not. Our senses tell us rings and red bendels, et al., do nothing. Subscribing to such imagined powers is a rejection of God's will for man to trust our senses.
These rings are idolatrous in nature and no different at all than the Egyptian idols and practices from which God saved us.
1. Baseless: no evidence
2. Contradiction: People don't live that way in in other areas of their lives. Tell believers in these rings/bendels to quit their job and rely on a ring or red bendel to provide their rent. They won't, since deep down, they don't believe in them.
3. Created vs. the Creator: Created things cannot deviate from their natural governing laws; they cannot control those laws or affect man's fate. Red bendels and rings burn in fire. If they cannot protect themselves, how can they protect anything/anyone else?
4. Inexplicable: When did these rings gain their "powers"? While still ore in the ground, no one would suggest they are different than any other element or contain powers. Once the ore is melted, but not yet a ring, is there power yet, or only once fashioned into jewelry? And what principle compels a person to suggest the power arrives in the ring at any step in the process? The failure of ring proponents to answer this question unveils their complete ignorance of their very claim. They accept what is inexplicable.