Diamond Dealers Club enforced handshake deals via trade exile

A diamond is close to the ideal object to steal or lie about: enormous value in a pocket-sized parcel, no serial number, resellable anywhere within hours. Dealers nonetheless need to trade constantly on credit and consignment with people they barely know, financing each other's inventory the way a bank finances a business, because no dealer holds enough capital to buy outright and no bank will underwrite gems it cannot itself value. A written, court-enforceable contract looks like the obvious safeguard for exposure like that.

It is also nearly useless for it. A civil suit over a stone worth a few hundred thousand dollars takes years to resolve, awards damages calculated by a judge with no feel for the market's swings, and becomes a public record the moment it is filed — which announces to every future counterparty that you were once burned, or that you are the kind of dealer who sues, either of which makes people stop dealing with you. By the time a judgment arrived it would often be worth less than the legal bill spent winning it.

Made expulsion from the global trade network the penalty, not lawsuits; a defaulter's name and photo spread worldwide, ending his career.

Court suits were slow, public, and poorly valued, so dealers avoided them.

A dealer's livelihood depended on staying in the global trading network.

Public expulsion from that network was a punishment no court could match.

The threat of exile made most pay quietly, so enforcement rarely needed testing.

When legal remedies are too slow or weak, make the penalty loss of access to the community that sustains a person's livelihood.

The threat is rarely tested because it does not need to be: a dealer risks his entire livelihood across every trading floor in the world to avoid paying a single disputed judgment, so the vast majority pay immediately and quietly. Legal scholar Lisa Bernstein's 1992 study of the system found dealers overwhelmingly preferring the club's arbitration to the courts even when courts were fully available to them, because the club's remedy — professional exile, publicly posted — was one no judge could ever hand down, and it worked faster and cost less than any lawsuit.