ROYAL BLUE
Sapphire
Provenance
The name "royal blue" appeared between 1810 and 1820. The "royal" in the name comes from the British royalty, where this shade of blue is said to have been created by a tailor in a competition to make a dress for Queen Charlotte in the early 19th century.
The blue associated with royal blue has actually changed over time. Prior to the 1950s, the original royal blue was considered much deeper than the official one approved in the 1980s by the World Wide Web Consortium, which associated the now lighter blue, along with its RGB code, with the name "Royal blue".
The original royal blue appears on the flag of the United Kingdom and is the colour closest to that used today for royal blue sapphire.
Royal Blue describes the sapphire with the most vivid and deepest saturation. It was probably first used by British gem trader to describe sapphire when Ceylon (now Sri Lanka) and Burma (now Myanmar) was part of the British Empire.
The symbolism of royal blue includes tranquility, as blue is the colour of the sky and the ocean, both of which are known to promote feelings of peace. The colour blue is synonymous with significance, importance and confidence. This is where the blue corporate suit and the blue uniforms around the world come from.
Definition
Colour has the greatest influence on the value of a sapphire. Royal blue describes sapphires with a pure blue to very slightly violetish blue hue, with a vivid saturation, which can in rare cases range from intense to deep, the tones should be medium to medium dark. For more information on colour classification, see here.
Clarity has a very important influence on the value of a sapphire. Royal blue sapphire must be flawless, preferably clean to the eye, or at least transparent, without pronounced inclusions that are very visible under the table. The colour uniformity must be excellent or evenly distributed.
Cut plays a very important role in the colour of a sapphire. Royal blue sapphires should have excellent to good proportions to maximise total internal reflection. Royal blue sapphires should not show significant windowing (transparent area) and/or extinction when viewed face up.
Treatment of Royal blue sapphire is acceptable only for no treatment or traditional heating. Therefore, any other treatment such as diffusion of foreign ions into the sapphire lattice, like beryllium or titanium, fracture sealing with resin, or lead, cobalt and/or silicate glass, will not be granted a gemmological report and as such not qualified for Royal blue or any other colour grading.
Blue sapphire master set. Reference collection Bellerophon Gemlab.
Science
The classification of the colour of a gemstone is both an art and a science. The adjective "Royal blue" combines many facts about a sapphire. Classifying the colour of a transparent anisotropic material like a blue sapphire is not as simple as it sounds. The hue, saturation and tones must fall within a predetermined range for the sapphire to be considered "royal blue".
The blue colour of sapphire is the result of a major chromophore: iron with titanium in pairs. It replaces some of the aluminium atoms in the structure, the more iron and titanium pairs, the bluer the sapphire all the way to black. The approximate iron and titanium content in most blue sapphire is between one to couples of tens of pairs of atom per million. Two other chromophores almost always play a role in blue sapphire: iron and chromium. The iron content tends to make the sapphire green, decreasing the blue saturation and increasing its tone, while chromium makes the sapphire violetish.
Quantifying the chromophores present in a sapphire provides a good starting point for colour comparison without the influence of other factors such as the path of light through the stone and reflections. By combining this method with the overall proportions of the stone, we can analyse the most influential colour factors separately and compare them to our reference collection of "Royal blue" sapphires.
Royal Blue Criteria
Hue
Tone
Saturation
Clarity
Homogeneity
Total Internal Reflection
Treatment
Blue to very slightly violetish blue
Medium to medium dark
Intense to vivid
Flawless to transparent
Excellent to very good
Excellent to very good (>70%)
None or traditional heating
