Is it permissible to wear smart rings for health tracking?

Smart rings, such as those referenced in your question, are generally made of titanium and stainless steel, usually decorated with other precious metals.

Therefore, these rings are not permissible in Islam for males and females. Only a single silver ring, weighing less than 1 Mithqaal (4.375g), is permitted for men, and only gold and silver rings are permitted for females. (Al-Fataawa al-Hindiyyah 5/335, al-Muheet al-Burhani 5/348)

Rings that have been gold or silver-plated will fall under the ruling of their plating. Hence, gold or silver-plated rings would be permitted for females to wear, and a silver-plated ring would be permissible for a male to wear. (al-Fataawa al-Hindiyyah 5/335)

There are alternatives, such as smart watches and bands, that provide convenience in communication and health tracking services.

And Allah Ta’ala Knows Best