Four pre-owned Love necklaces, and the differences are small and good. The yellow gold Love necklace has two interlocked Love rings on an 18k chain, and the rose gold one is a single Love ring with one diamond accent on a fine chain. The pre-owned 2 Diamonds Love pendant is yellow gold with two small diamonds, and the pre-owned Love Interlocking necklace pairs two rose gold rings, one of them diamond-set. My tip: if you layer, choose one of these and let it sit alone at the collarbone, then add a plain chain a few inches longer. Two Love pieces competing is how a neckline gets busy.

These are all pre-owned Juste un Clou pendants, and they show how far one nail can go. The yellow gold nail with a diamond-set head hangs on a cable chain, while the rose gold pave version is covered in diamonds on a link chain. The rose gold Juste un Clou with a diamond-set head sits on a fine 15 in chain, and the slim yellow gold one is the quietest of the four. Wear the pave one with a rough sweater, because the contrast is the whole joke. Wear the slim one under a shirt collar, open one button, and it looks like a secret.

The Trinity story is better than the legend. Cartier's archivists say the three-gold ring was made as a stock item, not specially commissioned, and the name came from Vogue. In this pre-owned set, the tricolor gold Trinity pendant and the tricolor Trinity chain necklace on a fine double chain both show yellow, rose and white gold at once. The three-tone Trinity with diamonds is the medium model on a black cord-style chain, and the white gold one adds black ceramic and diamonds. Tip: tricolor gold goes with every metal you already own, so wear it with your silver watch and stop worrying about mixing.

These four are for people who want a necklace you forget you are wearing. The pre-owned Diamants Légers d'Amour pendant is white gold with a single bezel-set diamond. The Amulette de Cartier is a small disc with a diamond at the center, here in onyx in extra small rose gold, in carnelian on a link chain, and in lapis lazuli on yellow gold. They read as jewelry first and a logo second. Tip: choose the stone that matches what you already wear most, so lapis if your closet is navy and denim, carnelian if it leans warm. What I would skip: stacking two Amulettes, because the discs crowd each other.

The last four have the most personality. Two pre-owned Panthère necklaces are yellow gold: one a panther-head pendant with green eyes on a double link chain, the other a small panther striding on a fine cable chain. The Panthère de Cartier is an articulated link necklace with diamond accents, and it moves like a bracelet at your neck. The vintage white gold LOVE charm on a 16 in chain with a lobster clasp is the understated one. If you are buying vintage, ask for the chain length first, because 16 in sits at the collarbone and that changes how every neckline looks.

With a Cartier necklace, choose the shape you would wear on a bad Monday, not the one you would wear to be photographed. A ring, a nail, a knot of three golds: each of these is small enough to wear daily and recognizable enough that people notice. Pre-owned and vintage pieces have a quiet advantage, which is that someone has already proved the design holds up.

The long grid above is where I would go once you already own one Cartier piece. The Tank aquamarine and the Etincelle heart are the softer ones, and the Clash and the French Maillon Panthère are the heavy pieces for people who want the necklace to be the outfit. Two more Amulettes join the stone story, one in rose gold guilloche and one with malachite for a green you have not seen yet, and the Trinity de Cartier in tricolor gold with rows of diamonds takes the knot to its biggest. The vintage diamond festoon is there for the opening line of this edit, the same shape Grace Kelly wore in 1956.

Pick one, wear it for a month, and then decide whether to add a second. If you want to keep browsing, I also put together Hermès Mini Kelly and Collar necklace.