"I'm not an expert. I've been reliably informed it's a sapphire with some diamonds. But I'm sure everyone recognises it from previous times.
Sapphires come in a large variety of colors, the most common of which is blue. However, it is popular to see Sapphires in a sunny yellow or a sunrise pink. However, the most valuable sapphires are a middle blue which remains constant under all lighting conditions
Sapphires are also the traditional gift for those celebrating 5th or 45th anniversaries. They are also often associated with loyalty and dignity making them favorites of royalty throughout history.
Sapphires get their colors the mineral corundum. It is turned to blue sapphire when it contains more iron and titanium, and pink or ruby depending on the levels of chromium.
Sapphire also has industrial use cases because of its hardness level of 9 on the Mohs scale, just below Diamonds. The Apple Watch and other glass screens feature lab-created sapphire glass.