What is a differential in green coffee pricing?

A differential is the premium or discount applied to a specific green coffee above or below the C-Market price, expressed in US cents per pound. Because most green coffee is traded with reference to the C-Market benchmark, the differential captures what distinguishes a particular coffee from the commodity baseline - its quality, origin reputation, traceability, or supply and demand at the lot level.

A "+45 cents over C" on an Ethiopian natural from a well-regarded washing station reflects the additional quality and demand that coffee commands beyond the market floor. A negative differential is rare in specialty but exists for lower-grade commercial material.

The practical implication: if you contract a coffee at "+30 over C" and the C-Market rises by 20 cents before delivery, your cost goes up proportionally - the differential stays fixed but the base price moves with the market. This is important to understand for anyone buying on differential-linked terms rather than a fixed price per kilo. It also means that when the C-Market spikes, well-sourced specialty coffees get more expensive even if nothing has changed about their quality or availability.