Mid-blue — The Trade Term for Commercial-grade Blue Sapphire
Mid-blue — The Trade Term for Commercial-grade Blue Sapphire
Medium tone and saturation, the colour space below Royal and Cornflower Blue
Mid-blue is a trade descriptor for blue sapphire of medium tone and saturation, occupying the colour space between light commercial material and the more saturated stones that earn premium colour calls such as Royal Blue or Cornflower Blue. The term is descriptive rather than a formal grading designation; it is used in dealer-to-dealer communication to indicate a stone whose colour is appealing and saleable but does not meet the threshold for the named premium grades.
Where mid-blue sits in the colour space
Tone in mid-blue typically runs from approximately 60 to 75 percent on the GIA scale — solidly medium, with the body of the stone clearly readable as blue rather than as black or as washed-out aqua. Saturation is sufficient for the colour to be visible across most face-up positions but does not approach the vivid, slightly violet-leaning purity of the Royal Blue benchmark or the open, clear character of fine Cornflower. Hue is generally pure blue or with a subtle violet secondary; pronounced grey or green secondaries push the stone out of the mid-blue category and into discounted commercial grades.
Trade usage
Mid-blue describes the bulk of the world's commercial sapphire production — Sri Lankan, Madagascan, Tanzanian, and East African material that is sold by colour rather than by origin. Dealers use the term to communicate quickly to buyers who do not need a formal report and who are working off photographs or video. The price band for mid-blue runs an order of magnitude below comparable Royal Blue or Cornflower stones and represents the workhorse colour space for mainstream coloured-stone retail.
The term is not used by the major laboratories on grading reports, which describe colour in formal hue-tone-saturation terms or by reference to internal benchmarks. A stone graded "violetish blue, medium-strong tone, strong saturation" by AGL would typically be sold as mid-blue to better mid-blue at trade level.