Size and surface are separate facts
A Chanel Flap listing may combine a size word, a leather finish and a hardware tone in one sentence. Those details do not replace one another. The published Small Flap is about 23 × 14.5 × 6–7 cm; the Medium is about 25.5 × 15.5–17 × 6.5–7 cm; the Jumbo is about 30 × 19.5 × 10 cm. Caviar is the pebbled calfskin surface that can appear on any of those bodies. Read the dimensions first, then use a close photograph to determine whether the grain is small, even pebbling or a larger visible texture.
The pebbled surface hides wear differently
Caviar grain interrupts reflected light, which makes small surface marks less obvious than they are on smooth lambskin. The trade-off is that the pebbled finish has a more structured visual line and can look firmer on a soft flap. Wear still appears at the folds, edges and corners, but it may follow the raised grains rather than a single continuous crease. Ask for close photographs of the flap edge, base corners and strap openings. Those are the places where surface condition is clearest and where a low-resolution catalogue image is least useful.
Strap drop belongs with the size
The Mini wears differently from the Small and Medium even when their widths are close. Published strap references include a fixed 58 cm single drop on the rectangular Mini and a roughly 42 cm single drop on the Small, while the Jumbo is commonly worn at about 33 cm doubled. A doubled chain changes where the bag sits under the arm, so the same 25 cm body can read formal or casual according to the carry. Record the single and doubled lengths separately and measure from the highest attachment point to the top edge.
Depth decides whether the flap closes
The Medium's depth is around 6.5 to 7 cm, while the Jumbo is about 10 cm. A 3 cm difference is enough to change how a wallet or phone sits without pressing the flap. A photograph taken straight from the front can show the body width but hides the gusset. Ask for a side view with the bag open and closed. The open view shows how much the sides can move; the closed view shows whether the flap returns to a clean line. A pebbled surface should still settle without a visible bulge at the turn-lock.
A four-part caviar confirmation
Record width across the base, height at the centre of the flap, depth at the base and the strap drop both doubled and single. Add an edge-on photograph of the grain and a close view of the turn-lock and chain. This separates a size question from a material question. If the dimensions point to a Small but the chain sits like a crossbody Mini, the attachment construction needs to be checked before the label is trusted. The measurements should match the shape; the material and hardware then complete the description.