Is 10k gold real gold?

Yes. 10k means 10 parts gold out of 24, so it is about 41.7% gold alloyed with other metals. It is real gold, but less pure and paler in color than 14k or 18k.

Is this chain strong enough for a pendant?

A 2.2mm solid cable chain can hold a small to medium pendant. Very heavy pendants put strain on fine links and on the clasp, so keep the pendant light relative to the chain.

What does diamond-cut mean?

The links are cut with angled facets that reflect light, which makes the chain look brighter and more sparkly than a plain polished cable chain. It is a finish, not a diamond setting.

Will 10k yellow gold tarnish or turn my skin green?

Solid 10k gold does not tarnish like plated jewelry, though it can dull over time and needs cleaning. Skin discoloration is usually from alloys in low-karat or plated pieces, not solid 10k gold.

How do I care for it?

Wipe it with a soft cloth and store it dry and separate from other chains to avoid scratches. Take it off before swimming, showering or using harsh cleaners.