Are there any gems in the crown of the old Cartier watch?

Yes, kyanite is usually used for decoration.

Kyanite, sapphire, is the general name of corundum gemstones with other colors except ruby, and its main component is alumina (Al2O3). Blue sapphire is caused by a small amount of titanium (Ti) and iron (Fe) impurities. Sapphire can be pink, yellow, green, white, or even multiple colors in the same stone. Sapphire is produced in Thailand, Sri Lanka, Madagascar, Laos, Cambodia, China, Changle, Hainan, and Sun Shi Mountain in Jiangjin, Chongqing. Among them, the rarest origin belongs to the sapphire in Kashmir, and Myanmar is the place where the highest quality sapphire is produced today.

Sapphire is characterized by uneven color, and parallel hexagonal columns are arranged with flat bands and growth lines of different shades. Poly-sheet has the development of bimorph, and the bimorph pattern of louver is common. Cleavage often cleaves along double crystal planes. Dichroism is strong. In addition to the above characteristics, sapphires all over the world have their own characteristics due to different places of origin. In 1980s, many sapphire deposits were discovered in basalt along the eastern coast of China.