Is moissanite a good diamond substitute here?

Yes for looks. Moissanite has more fire and brilliance than a diamond and rates VVS in clarity, so it reads bright and clean. It is not a diamond, so it will not hold resale value the way one does.

Will the gold plating last?

Vermeil is a thick gold layer over sterling or base metal, and it holds up better than thin plating but still wears at high-friction points. Take it off for showers, swimming and workouts to extend its life.

Is this necklace for men or women?

Both. GLD lists it as unisex, and the 3mm curb chain with a tennis line suits either. The width is bold enough for a men's look and still fine for women.

How wide is it and how does it sit?

The stones are set in a 3mm-wide line, which is a substantial tennis style rather than a delicate one. Expect it to sit flat against the neck and read as a statement piece.

What should I know about care?

Keep it away from water, perfume, lotion and chlorine, and wipe it with a soft cloth after wear. Store it separately so the curb links and settings do not scratch.