Can a wrong gemstone harm me? Are cheaper substitute stones okay?

tradition says a wrongly chosen gem can disturb; if in doubt, don't wear one — substitutes, mantras and dāna are gentler options.

Astrologers who use gems believe they amplify a planet's influence, so a gem chosen for the wrong planet is thought to bring restlessness, quarrels or setbacks. Whether or not you hold that belief, the practical lesson is the same: do not wear powerful stones on the advice of a random video or a shop salesman.

Substitute stones (uparatna) — for example garnet for ruby, moonstone for pearl, peridot or green tourmaline for emerald, yellow topaz for yellow sapphire, amethyst for blue sapphire — are traditionally considered milder and are often suggested when the main gem is too costly. Fake or treated stones sold as “natural” are a real problem, so ask for a lab certificate.

If you feel uneasy after wearing a stone, it is perfectly fine to remove it. A mantra or a regular act of charity carries no such risk.

Source: modern practice · Ask for a gem-lab certificate

Dharma Q&A — Jyotiṣa, scriptures & modern life · Ask a Jyotishi your own question