Editing Carat (mass) (section)

=== UK Board of Trade ===
In the [[United Kingdom]] the original '''[[Board of Trade]] carat''' was exactly {{frac|3|1647|9691}} [[Grain (unit)|grain]]s (~3.170&nbsp;grains = ~205&nbsp;mg);{{efn-lr|The pre-1888 [[Board of Trade]] carat, of which there were exactly {{frac|151|27|64}} per [[ounce#International troy ounce|ounce troy]], was approximately {{cvt|205.4094|mg}}.}} in 1888, the Board of Trade carat was changed to exactly {{frac|3|17|101}} grains (~3.168&nbsp;grains = ~205&nbsp;mg).{{efn-lr|The post-1887 Board of Trade carat, of which there were exactly {{frac|151|1|2}}; per ounce troy, was approximately {{cvt|205.3035|mg}}.}} Despite it being a non-metric unit, a number of metric countries have used this unit for its limited range of application.

The Board of Trade carat was divisible into four ''diamond grains'',{{efn-lr|Unlike the modern carat, the Board of Trade carat was not used for measuring pearls; those were measured with ''pearl grains''.}} but measurements were typically made in multiples of {{frac||1|64}} carat.