Definition:Troy

Definition
The troy (system of) weights is a system of mass units used, but rarely, for precious metals

It descends from the system of weights used by the Romans.

Although in some cases bearing the same names as their imperial counterparts, the actual units themselves were subtly different in size.

The units do in fact coincide with the units of the same name in the apothecaries' system.

Also see

 * Definition:Imperial
 * Definition:Apothecaries' Weights and Measures