Sapphire & Ruby: the stars of jewelry

Twin stones 

The sapphire And the ruby are precious stones both from the corundum family. What differentiates them is the chromium content contained in a red-colored corundum (the ruby), and the iron and titanium content contained in a blue corundum (the sapphire). Corundums of other colors are also sapphires, which is a so-called “allochromatic” stone that comes in yellow, green, orange, pink, purple, etc. depending on the chemical elements that compose it. Note that the mention "sapphire" alone" means by default that it is a blue sapphire. 

Regarding their hardness, corundums are rated at 9th position on the Mohs scale; they are placed just below the diamond, the hardest stone of all. This characteristic therefore explains their strong presence in the world of jewelry, or these precious stones are easily crimped and can subsequently be worn daily without risk.

Star stones

In addition to its known characteristics, there are others that are just as fascinating and yet little used in jewelry. In particular, the presence of asterisms on some of the corundums, which draw a star of 4 or 6 branches on the surface of the stone most frequently, which can go up to 12. This phenomenon is due to the interference of light with a large quantity of inclusions called “silks,” which are actually fine needles of rutile, composed of titanium. This phenomenon is highlighted by the cabochon cut corundums, except today, in jewelry, precious stones are mostly cut with facets.

Historically, one of the largest star sapphires ever found is the 182-carat “Star of Bombay,” found in Sri Lanka, the largest corundum deposit. Today, this stone is kept at the Smithsonian Institution in Washington.

Royal stones

In addition to being able to adorn themselves with a star, these two star stones also have been worn on numerous occasions by royal heads which accentuated their desirability. Here are some examples:

In 1762, the Russian Imperial Crown, made for the coronation of Catherine II, was adorned with a huge Burmese ruby of 398.72 carats. This stone is one of the largest and most impressive ever mounted on a royal crown.

In 1981, Prince Charles presented Lady Margaret with a 12-carat sapphire ring. Diana, making sapphire a symbol of royal love... It is now worn by Kate Middleton. 

In 2013, another ring adorned with an even more historic sapphire was sold at auction: that of Napoleon Bonaparte at Joséphine.