Is this necklace solid gold or plated?

GLD lists both 14k and 18k options, and the material line mentions rose gold plated alongside rose gold. Check the specific karat option you pick: solid gold holds up for years, while plated versions wear faster with daily use.

How wide is it, and is 8mm too chunky?

The links are 8mm wide, which is on the bold side for a chain necklace. It reads as a statement piece rather than a subtle everyday chain, so it suits people who like visible jewelry.

What length is it, and can it be adjusted?

It comes in one size at 18 inches, a collarbone length for most wearers. There is no extender, so shorter or longer necks may find the fit off.

Does it work for layering?

Yes, but the 8mm width makes it the heaviest piece in a stack. Pair it with a thin chain or a pendant on a shorter length so the baguette links stay the focus.