Lot mix is the trade-floor description of how a parcel is built up. A parcel of a kilogram of rough sapphire is not a homogeneous unit; it contains a distribution of sizes, of colours, of clarities, and of yieldable goods. The 'mix' is the language used by buyer and seller to summarise that distribution before either side commits to a price.

Reading a mix

An experienced buyer will rough-sort a parcel into bands - top goods, middle, commercial, and rejects - and assess the proportion in each band. A 'top-heavy' mix has more high-end material than the parcel's price suggests; a 'tail-heavy' mix is dominated by lower goods that drag the average down. Mining-source parcels typically run tail-heavy; pre-sorted parcels at the dealer level usually have a tighter, more predictable mix because the seller has already creamed the exceptional goods for separate sale.

Why it drives price

A parcel is priced on the average yieldable value of its mix, not on its best stone. Two parcels of identical weight and origin can transact at very different prices if their mix differs, and the dealer who can read mix faster than the competition - in poor light, under time pressure, with a partial sample of the parcel exposed - is the dealer who consistently buys well.