No, this pendant is not a proven shield against electromagnetic fields or radiation. The product information describes shungite's fullerene-like carbon structures as a reason for scientific and folk interest, and in folk practice people often keep shungite near phones, computers and electronics because of its traditional association with protection from a technology-heavy environment.
It is more honest, however, to see the pendant as a wellness accessory than as a defence against EMF. There is no evidence in the product information that the stone blocks, absorbs or neutralises any form of electromagnetic emission. If your real concern is screen time, posture or sleep, wearing the pendant will not replace practical measures like taking breaks, reducing device use in the evening or adjusting your desk setup.
That does not mean the pendant is useless. The flat 30 mm stone gives you something to touch or adjust during the day, and for some people that sensory anchor helps create a sense of focus and steadiness. In that way, it can support better habits — a short walk away from the screen, a pause to breathe, a reminder to check in with yourself — but it should not carry the burden of a medical or technological claim. Keep your expectations realistic, and treat the stone as a pleasant part of a broader routine rather than as a protective barrier.