length · Gemological reporting · Modern

gemstone dimensions

exact

Record: M561
Definition quality: Standardized
Conversion mode: contextual
Calculator: Context required

Definition

Gem grading reports state physical dimensions in millimetres; for round diamonds typically min diameter–max diameter × depth, and for fancy shapes length × width × depth.

Reference value

One gemstone dimensions is exactly 0.001 metres.

History & use

GIA explicitly warns that equal carat weights do not guarantee equal physical size because density and cut proportions differ.

Modern use

Modern use is context-dependent and varies by region or measurement system.

Sources & evidence

Source tier — · confidence high

Related measurements

metre

length · International · Modern

SI base unit of length. Its definition fixes the speed of light in vacuum at exactly 299,792,458 m/s, with the second defined from the caesium-133 hyperfine frequency.