The Edit

Hallmarks, magnets, water density and acid: which home tests for gold work, which mislead, and the figures for 10K, 14K and 18K.

Thin bands, worn prongs and hard knocks: why rings fail, which settings hold stones best, and the checks that prevent it.

Why 14K gold scratches, why 10K is harder than 18K, and what Vickers and Mohs numbers mean for jewelry you wear every day.

Green, black or red marks under jewelry: what causes each, whether solid gold is to blame, and how to stop it.

Water won’t hurt solid gold. Chlorine, soap and grit can. What to keep on and what to take off.

Lobster, spring ring, box, toggle and hinged closures: how each works, how to open the tricky ones, and how to keep a bracelet on.

The Pink Star, the Blue Moon, the Hope and the Cullinan: what the most expensive diamonds sold for, and why.

They look alike in the case. How white gold and sterling silver differ in price, wear, tarnish and upkeep.

As hard as mined diamond, and no tougher: what really chips a lab-grown diamond, and how to make one last.

Turning 21 on the 21st: where the golden birthday came from, when yours falls, and how to mark it.