The Cartier grid runs from a $925 Trinity cord bracelet to a $6,300 Love cuff, and almost everything in it belongs to one of four families: Love, Juste un Clou, Trinity and Clash. That concentration is deliberate on Cartier's part and it helps a buyer, because a piece from a long running collection can be compared against dozens of other listings and against a current retail price. Two practical notes. Love pieces are screwed rather than clasped, and the screws wear, so a listing that mentions the screwdriver or the original screws is worth more than one that does not. And Cartier gold is usually eighteen carat with a stamped serial number, so a listing photograph showing the interior engraving is the single most useful image on the page. The Amulette and the Damour pendant here are the quieter end of the house, and they trade at a discount to the Love pieces for recognition reasons rather than quality ones.

The Van Cleef grid runs from $1,600 to $10,000 and it is dominated by Alhambra, which is the correct outcome rather than a gap in the selection. The four leaf clover motif has been in continuous production since nineteen sixty eight and it accounts for the large majority of the house's secondhand volume. The variables are the stone and the count: onyx, carnelian, malachite, mother of pearl, and whether the piece has five motifs, ten, twenty or one. Price tracks the count and the stone rarity closely, which makes this the easiest of the two houses to price sanity check. The stones matter for a practical reason too. Malachite and mother of pearl are soft and can chip on an edge, while onyx and carnelian are harder and survive daily wear better. The Frivole and Fleurette pieces here are the diamond side of the house and they behave like conventional fine jewelry, where the setting is what to inspect.

With both houses the purchase is really about provenance, because the designs are so widely copied that condition is the second question rather than the first. Prefer listings that show the interior hallmark and serial number, that name the authentication, and that include original documentation where it exists. Cartier's Love and Juste un Clou are the most liquid pieces and therefore the easiest to price check against other listings. Van Cleef's Alhambra is equally liquid, and if you intend to wear it every day choose onyx or carnelian over malachite or mother of pearl, since the softer stones chip at the edges. If you take one thing away, let it be to buy the piece with the paperwork rather than the piece in slightly better condition, because on these two names the documentation is worth more than the polish.