Topaz and citrine. Topaz is the older of the two; citrine was added to the modern list as a more affordable alternative and is now the more commonly worn. Citrine is the traditional gift for a thirteenth anniversary, topaz for a fourth.

They look similar in yellow, but they're unrelated minerals. Citrine is a quartz — 7 on the Mohs scale, and the more affordable of the two. Topaz is harder at 8, denser in the hand, and occurs in a far wider range of colours, from colourless through blue to a pink-orange that's the most valuable of all.

Citrine runs from pale lemon to a deep brandy orange, with the warmer, more saturated stones generally the more prized. Topaz covers much more ground — blue, colourless, pink, yellow and orange all occur naturally.

Citrine is tied to abundance and warmth — it was known as the merchant's stone, carried for prosperity. Topaz takes its name from a Sanskrit word for fire, and has long been associated with strength and clear thinking.

It's hard — 8 on the Mohs scale, above quartz and most coloured stones. The one thing to know is that topaz has a cleavage plane, so a sharp knock in the wrong direction can split it in a way that a scratch never would. Treat it well and it lasts indefinitely.

Yes. Citrine is a quartz at 7 on the Mohs scale, the same hardness as amethyst, with no cleavage to worry about. It's one of the more forgiving stones to wear daily.